Revert "disp: msm: sde: use mdp scratch register to pass drm mode info"

This reverts commit e8309fcb. Removing
the scratch register logic to pass information between the VMs as the
design changed from kernel to user-mode for passing the mode information
through qrtr from primary-vm to trusted-vm.

Change-Id: Ibfa4b0004496f68b272da808e866f5226b02c013
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>