scripts/kernel-doc: change the line number meta info

In order to make it more standard and ReST compatible,
change the meta-tag used with --enable-lineno from:

        #define LINENO

to
        .. LINENO

In practice, no	functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/40725032b5a4a33db740bf1de397523af958ff8a.1648290305.git.mchehab@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Author: mchehab

Documentation/sphinx/kerneldoc.py

@@ -130,7 +130,7 @@ def run(self):
             result = ViewList()
 
             lineoffset = 0;
-            line_regex = re.compile("^#define LINENO ([0-9]+)$")
+            line_regex = re.compile("^\.\. LINENO ([0-9]+)$")
             for line in lines:
                 match = line_regex.search(line)
                 if match:

scripts/kernel-doc

@@ -424,7 +424,7 @@ sub get_kernel_version() {
 sub print_lineno {
     my $lineno = shift;
     if ($enable_lineno && defined($lineno)) {
-        print "#define LINENO " . $lineno . "\n";
+        print ".. LINENO " . $lineno . "\n";
     }
 }
 ##
@@ -2478,7 +2478,7 @@ May be specified multiple times.
 
 =item -enable-lineno
 
-Enable output of #define LINENO lines.
+Enable output of .. LINENO lines.
 
 =back