drm/msm: Remove dpu_encoder_phys_ops->hw_reset()

We call out of the virt encoder into phys only to call back into the
virt for hw reset. So remove the indirection and just call the virt
function directly.

Reviewed-by: Jeykumar Sankaran <jsanka@codeaurora.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>