drm/gud: cleanup coding style a bit

[ Upstream commit 6dd7efc4

 ]

Fix coccicheck warning:
drivers/gpu/drm/gud/gud_internal.h:89:2-3: Unneeded semicolon
drivers/gpu/drm/gud/gud_internal.h:107:2-3: Unneeded semicolon

Signed-off-by: Bernard Zhao <bernard@vivo.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210402085523.76928-1-bernard@vivo.com