scsi: docs: Add description for missing options of link_power_management_policy

With the kernel update we have more different policy for SCSI
link power management. Add the corresponding description to
the file.

Signed-off-by: Yiwei Lin <s921975628@gmail.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260115065341.10230-1-s921975628@gmail.com>

Author: RinHizakura

Documentation/scsi/link_power_management_policy.rst

@@ -5,13 +5,13 @@ Link Power Managent Policy
 ==========================
 
 This parameter allows the user to set the link (interface) power management.
-There are 3 possible options:
+There are 6 possible options:
 
-=====================   =====================================================
+======================  =====================================================
 Value			Effect
-=====================   =====================================================
-min_power		Tell the controller to try to make the link use the
-			least possible power when possible.  This may
+======================  =====================================================
+min_power		Enable slumber mode(no partial mode) for the link to
+			use the least possible power when possible.  This may
 			sacrifice some performance due to increased latency
 			when coming out of lower power states.
 
@@ -22,4 +22,15 @@ max_performance		Generally, this means no power management.  Tell
 medium_power		Tell the controller to enter a lower power state
 			when possible, but do not enter the lowest power
 			state, thus improving latency over min_power setting.
-=====================   =====================================================
+
+keep_firmware_settings	Do not change the current firmware settings for
+			Power management. This is the default setting.
+
+med_power_with_dipm	Same as medium_power, but additionally with
+			Device-initiated power management(DIPM) enabled,
+			as Intel Rapid Storage Technology(IRST) does.
+
+min_power_with_partial	Same as min_power, but additionally with partial
+			power state enabled, which may improve performance
+			over min_power setting.
+======================  =====================================================