drm/msm: unify MDSS drivers

MDP5 and DPU1 both provide the driver handling the MDSS region, which
handles the irq domain and (incase of DPU1) adds some init for the UBWC
controller. Unify those two pieces of code into a common driver.

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/482506/
Link: https://lore.kernel.org/r/20220419155346.1272627-2-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>