Documentation: intel_pstate: fix duplicate hyperlink target errors

Fix reST warnings in
Documentation/admin-guide/pm/intel_pstate.rst caused by missing explicit
hyperlink labels for section titles.

Before this change, the following errors were printed during
`make htmldocs`:

  Documentation/admin-guide/pm/intel_pstate.rst:401:
    ERROR: Indirect hyperlink target (id="id6") refers to target
    "passive mode", which is a duplicate, and cannot be used as a
    unique reference.
  Documentation/admin-guide/pm/intel_pstate.rst:517:
    ERROR: Indirect hyperlink target (id="id9") refers to target
    "active mode", which is a duplicate, and cannot be used as a
    unique reference.
  Documentation/admin-guide/pm/intel_pstate.rst:611:
    ERROR: Indirect hyperlink target (id="id15") refers to target
    "global attributes", which is a duplicate, and cannot be used as
    a unique reference.
  ERROR: Duplicate target name, cannot be used as a unique reference:
  "passive mode", "active mode", "global attributes".

These errors occurred because the sections "Active Mode",
"Active Mode With HWP", "Passive Mode", and "Global Attributes"
did not define explicit hyperlink labels. As a result, Sphinx
auto-generated duplicate anchors when the same titles appeared
multiple times within the document.

Because of this, the generated HTML documentation contained
broken references such as:

  `active mode <Active Mode_>`_
  `passive mode <Passive Mode_>`_
  `global attributes <Global Attributes_>`_

This patch adds explicit hyperlink labels for the affected sections,
ensuring all references are unique and correctly resolved.

After applying this patch, `make htmldocs` completes without
any warnings, and all hyperlinks in intel_pstate.html render properly.

Signed-off-by: Swaraj Gaikwad <swarajgaikwad1925@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
[ rjw: Subject adjustment ]
Link: https://patch.msgid.link/20251029134737.42229-1-swarajgaikwad1925@gmail.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: Swaraj-1925

Documentation/admin-guide/pm/intel_pstate.rst

@@ -62,6 +62,8 @@ a certain performance scaling algorithm.  Which of them will be in effect
 depends on what kernel command line options are used and on the capabilities of
 the processor.
 
+.. _Active Mode:
+
 Active Mode
 -----------
 
@@ -94,6 +96,8 @@ Which of the P-state selection algorithms is used by default depends on the
 Namely, if that option is set, the ``performance`` algorithm will be used by
 default, and the other one will be used by default if it is not set.
 
+.. _Active Mode With HWP:
+
 Active Mode With HWP
 ~~~~~~~~~~~~~~~~~~~~
 
@@ -192,6 +196,8 @@ This is the default P-state selection algorithm if the
 :c:macro:`CONFIG_CPU_FREQ_DEFAULT_GOV_PERFORMANCE` kernel configuration option
 is not set.
 
+.. _Passive Mode:
+
 Passive Mode
 ------------
 
@@ -432,6 +438,8 @@ the ``energy_model`` directory in ``debugfs`` (typlically mounted on
 User Space Interface in ``sysfs``
 =================================
 
+.. _Global Attributes:
+
 Global Attributes
 -----------------