drm: Add acquire ctx to ->gamma_set hook

Atomic helpers really want this instead of the hacked-up legacy
backoff trick, which unfortunately prevents drivers from using their
own private drm_modeset_locks.

Aside: There's a few atomic drivers (nv50, vc4, soon vmwgfx) which
don't yet use the new atomic color mgmt/gamma table stuff. Would be
nice if they could switch over and just hook up
drm_atomic_helper_legacy_gamma_set() instead.

Cc: Dave Airlie <airlied@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Sinclair Yeh <syeh@vmware.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: Eric Anholt <eric@anholt.net>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170403083304.9083-13-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 0a3d91c..25569e5 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -3479,6 +3479,7 @@ EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);
  * @green: green correction table
  * @blue: green correction table
  * @size: size of the tables
+ * @ctx: lock acquire context
  *
  * Implements support for legacy gamma correction table for drivers
  * that support color management through the DEGAMMA_LUT/GAMMA_LUT
@@ -3486,7 +3487,8 @@ EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);
  */
 int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
 				       u16 *red, u16 *green, u16 *blue,
-				       uint32_t size)
+				       uint32_t size,
+				       struct drm_modeset_acquire_ctx *ctx)
 {
 	struct drm_device *dev = crtc->dev;
 	struct drm_mode_config *config = &dev->mode_config;