checkpatch: prefer MODULE_LICENSE("GPL") over MODULE_LICENSE("GPL v2")

There is no effective difference.

Given the large number of uses of "GPL v2", emit this message only for
patches as a trivial treeside sed could be done one day.

Ref: commit bf7fbeea ("module: Cure the MODULE_LICENSE "GPL" vs. "GPL v2" bogosity")

Link: https://lkml.kernel.org/r/20220128185924.80137-1-joe@perches.comSigned-off-by: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -7418,6 +7418,13 @@ sub process {
 				WARN("MODULE_LICENSE",
 				     "unknown module license " . $extracted_string . "\n" . $herecurr);
 			}
+			if (!$file && $extracted_string eq '"GPL v2"') {
+				if (WARN("MODULE_LICENSE",
+				     "Prefer \"GPL\" over \"GPL v2\" - see commit bf7fbeeae6db (\"module: Cure the MODULE_LICENSE \"GPL\" vs. \"GPL v2\" bogosity\")\n" . $herecurr) &&
+				    $fix) {
+					$fixed[$fixlinenr] =~ s/\bMODULE_LICENSE\s*\(\s*"GPL v2"\s*\)/MODULE_LICENSE("GPL")/;
+				}
+			}
 		}
 
 # check for sysctl duplicate constants