drm/msm/dpu: move resource allocation to the _probe function

To let the probe function bail early if any of the resources is
unavailable, move resource allocattion from kms_init directly to the
probe callback. While we are at it, replace irq_of_parse_and_map() with
platform_get_irq().

This also drops devm_iounmap() calls. It is too early to have them
_dpu_kms_hw_destroy() (or it will break if for some reason DPU device is
rebound into the composite device) and it doesn't make sense to have
them in dpu_dev_remove (as everything will be torn down by the devres
anyway after the device is unbound from the driver).

Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/561629/


Signed-off-by: Rob Clark <robdclark@chromium.org>