drivers: gpu: Mark function as static in radeon_kms.c

Mark function radeon_info_ioctl() as static in drm/radeon/radeon_kms.c
because it is not used outside this file.

This eliminates the following warning in drm/radeon/radeon_kms.c:
drivers/gpu/drm/radeon/radeon_kms.c:194:5: warning: no previous prototype for ‘radeon_info_ioctl’ [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_kms.c

@@ -191,7 +191,7 @@ static void radeon_set_filp_rights(struct drm_device *dev,
  * etc. (all asics).
  * Returns 0 on success, -EINVAL on failure.
  */
-int radeon_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
+static int radeon_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 {
 	struct radeon_device *rdev = dev->dev_private;
 	struct drm_radeon_info *info = data;