drm/gem-shmem: Fix the MODULE_LICENSE() string

Replace the bogus "GPL v2" with "GPL" as MODULE_LICNSE() string. The
value does not declare the module's exact license, but only lets the
module loader test whether the module is Free Software or not.

See commit bf7fbee ("module: Cure the MODULE_LICENSE "GPL" vs.
"GPL v2" bogosity") in the details of the issue. The fix is to use
"GPL" for all modules under any variant of the GPL.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Fixes: 4b2b5e1 ("drm: Move GEM memory managers into modules")
Link: https://patch.msgid.link/20251209140141.94407-3-tzimmermann@suse.de

Author: tdz

drivers/gpu/drm/drm_gem_shmem_helper.c

@@ -896,4 +896,4 @@ EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_no_map);
 
 MODULE_DESCRIPTION("DRM SHMEM memory-management helpers");
 MODULE_IMPORT_NS("DMA_BUF");
-MODULE_LICENSE("GPL v2");
+MODULE_LICENSE("GPL");