drm/gma500/cdv: Add and hook up chip op for disabling sr

Add a callback hook to the chip ops struct to allow chips to have their
specific self-refresh function. Currently only used by cdv.

Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
diff --git a/drivers/gpu/drm/gma500/cdv_device.c b/drivers/gpu/drm/gma500/cdv_device.c
index 747d903..162f686 100644
--- a/drivers/gpu/drm/gma500/cdv_device.c
+++ b/drivers/gpu/drm/gma500/cdv_device.c
@@ -657,4 +657,5 @@
 	.power_down = cdv_power_down,
 	.power_up = cdv_power_up,
 	.update_wm = cdv_update_wm,
+	.disable_sr = cdv_disable_sr,
 };