msm: mdss: support wfd and rotation simultaneously

Concurrent rotation and WFD usecases need to be supported
using a single writeback hw module for low end targets.
To enable this feature, mixer, ctl and DMA pipe needs to be
shared between block and line mode operations and hardware
programing is synchronized with a shared mutex.

Change-Id: I0fe909dd07006282239c65d5fe92d270069a3920
Signed-off-by: Sree Sesha Aravind Vadrevu <svadrevu@codeaurora.org>