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 --cc drivers/gpu/drm/gma500/cdv_device.c
Simple merge

diff --cc drivers/gpu/drm/gma500/cdv_device.h
Simple merge

diff --cc drivers/gpu/drm/gma500/cdv_intel_display.c
Simple merge

diff --cc drivers/gpu/drm/gma500/gma_display.c
Simple merge

diff --cc drivers/gpu/drm/gma500/gma_display.h
Simple merge

diff --cc drivers/gpu/drm/gma500/psb_drv.h
Simple merge