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
libcopybit: Add missing return statement

Change-Id: I662699b7418eba2c4792ed6c7c7b628762ebe03b
(cherry picked from commit f2e940109252c63b6e21f929e45ba794dfe12b95)
copybit: Fix type conversion error for GCC 4.7

    GCC 4.7 has stricter type conversion rules in copybit.cpp

Change-Id: I7f8572e2d9416ccb2ba17e707c7f75a2e69d69cf
hwc: For FB target check RGB pipe availability before VG pipe

If RGB pipe is available then it should be allocated before
allocating VG pipe for FB target.

Change-Id: I0c1f0fd08a7779eb077e9e9c1809bdbcaff2227c
hwc: Disable mdp comp if mDownscaleMode is set for external

If mDownscaleMode is on then scaling will be done. Sending a RGB
layer with alpha to VG pipe can cause composition issues.

Change-Id: I215a5d7360fe741124e809be0b66c328c943d7dc
overlay: Allocate from MM heap as a fallback

 * Not all devices support IOMMU yet, so use the MM heap as a fallback.
 * Enabled when NO_IOMMU is set

Change-Id: I9d9f3dffb92f5b4bf45422df0f66a40611943202
display: Cover NO_IOMMU for msm7x30/msm7x27a too

Change-Id: Ic68672f386a06fd0ac9fd1f18eec3188415a8642
hwc: rotator is not supported on msm7x27a

Change-Id: I26fe237831eb6fa41968d5eb6a75938e6dc53183
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_hardware_qcom_display-caf into HEAD