drm/msm: move irq utils to mdp_kms

We'll want basically the same thing for mdp5, so refactor it out so it
can be shared.

Signed-off-by: Rob Clark <robdclark@gmail.com>

diff --cc drivers/gpu/drm/msm/Makefile
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp4/mdp4_crtc.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp4/mdp4_dtv_encoder.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp4/mdp4_irq.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp4/mdp4_kms.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp4/mdp4_kms.h
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp4/mdp4_plane.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp_kms.c
Simple merge

diff --cc drivers/gpu/drm/msm/mdp/mdp_kms.h
Simple merge

diff --cc drivers/gpu/drm/msm/msm_kms.h
Simple merge