msm: mdss: add error check for iommu attach API

Iommu device attach api returns error code if it fails.
MDP driver will check this error code and fall back to
recovery path if device attach fails.

Change-Id: I2b9d2d3aa16bc814739e466e9fc5a2c51c7b2b4b
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>
Signed-off-by: Vineet Bajaj <vbajaj@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_mdp_overlay.c
msm: mdss: IOMMU ref count implementation

Currently MDP is attaching/detaching iommu based on
bus bandwidth requests. This can lead to performance
issues, so implement ref count on iommu such that
iommu is attached where needed.

Change-Id: Ic4d35e2dc7f83291d1ab93d3e0109a2d69c98844
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>
Signed-off-by: Vineet Bajaj <vbajaj@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_dsi_host.c
	drivers/video/msm/mdss/mdss_mdp.c
	drivers/video/msm/mdss/mdss_mdp_overlay.c
msm: mdss: Cleanup iommu ref count implementation

With current iommu ref count implementation, iommu is
attached at points when only needed and detached once
finished. Iommu reference count in overlay pan display
path is currently missing hence add it. Also remove
code repetitions and unnecessary error checks while
decreasing iommu ref counts in overlay and writeback
path.

Change-Id: If1aed768e5d704dd6c9d4bfd17c1ec368c8d8711
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>
Signed-off-by: Vineet Bajaj <vbajaj@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_mdp_overlay.c
msm: mdss: fix IOMMU page fault when fb splash logo enabled

This fixes the IOMMU page fault seen when fb splash logo is
enabled. If fb splash logo is enabled pan display gets called
with continuous splash enabled. During this time iommu attach
should not be called.

Change-Id: I59ac704c6fd77a7e731db0b544338cac3b8e8fe6
Signed-off-by: Vineet Bajaj <vbajaj@codeaurora.org>