msm: mdp3: Map splash addr before smmu attach

During bootup while continuous splash is enabled for video mode panel,
iommmu page fault seen for first iommu attach. As DMA transfer is
active during continuous splash, need to map the splash addr before
iommu is attached.

Change-Id: I7596a5bfb0fe36d037c63f9b7fff2dce7ab8998f
Signed-off-by: Raghavendra Ambadas <rambad@codeaurora.org>