liboverlay: do not return error if fb num >= 2 doesn't exist (writeback).

Some devices doesn't have writeback support, but needs HDMI (fb1)
This will allow them not to break HDMI support.
This is a cleaner implementation as it won't change handling on
8660 devices having writeback (if those exists).

Change-Id: I6c09759dfa4f2b1734f85012cab4eb4f350820ea
hwc: Blank and unblank primary on first boot for msm7x30

I made this commit to workaround a strange issue we faced on our Samsung Galaxy S Plus (GT-I9001)
after switching to ION and updated Adreno drivers (Vanilla drivers released on April 2013 by Qualcomm).

After completing the boot and before the first screen off, sometimes the boot splash screen appeared
during app transitions, instead of completely blank screen, for example when starting video playback,
while the first load of the keyboard... The problem happened on CM 10.2 and CM 11.0, not on CM 10.1.

I haven't found another solution at the moment, but probably we're missing something on kernel side (framebuffer driver).

Change-Id: Ib57ae5bf43ac46f2b6d7bd6f3473be5ca529f7a8
overlay: Allocate from MM heap as a fallback

 * Not all devices support IOMMU yet, so use the MM heap as a fallback.

Change-Id: I9d9f3dffb92f5b4bf45422df0f66a40611943202
hwcomposer: Use RGB_BORDERFILL only on MDP 4.2 and higher.

MDP 4.0 does not support RGB_BORDERFILL and causes the display to fail
initializing.

Patch Set 2: Actually set MDP_RGB format if not BORDERFILL.

Change-Id: Ib2007221c4dc78fd17ced97c0a0d28896c877b80
gralloc : Don't fallback to system heap for framebuffer allocations

MDP can not handle buffers from system heap, so try camera heap
first, before falling back completely to system heap

Change-Id: I7e2ab0094be5d1075be1ca93295cf54b84101835
display: Cover NO_IOMMU for msm7x30 too

Change-Id: Ic68672f386a06fd0ac9fd1f18eec3188415a8642