drm: Pass the user drm_mode_fb_cmd2 as const to .fb_create()

Drivers shouldn't clobber the passed in addfb ioctl parameters.
i915 was doing just that. To prevent it from happening again,
pass the struct around as const, starting all the way from
internal_framebuffer_create().

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 71860f8..9f02a09 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14377,7 +14377,7 @@
 static struct drm_framebuffer *
 intel_user_framebuffer_create(struct drm_device *dev,
 			      struct drm_file *filp,
-			      struct drm_mode_fb_cmd2 *user_mode_cmd)
+			      const struct drm_mode_fb_cmd2 *user_mode_cmd)
 {
 	struct drm_i915_gem_object *obj;
 	struct drm_mode_fb_cmd2 mode_cmd = *user_mode_cmd;