android: drop HAL_PIXEL_FORMAT_RGBA_{5551,4444}

android: drop HAL_PIXEL_FORMAT_RGBA_{5551,4444}

Upstream Android (system/core) has dropped these formats with commit
6bac41f1bf9(get rid of HAL pixelformats 5551 and 4444) yet does not
mention why.

These formats never really worked so we're safe to drop them as well.

Identical commit is available in the android-x86 external/mesa repo

    commit 06a2d36edcd1e2247440e5800e6bf3028f37aee6
    Author: Chih-Wei Huang <cwhuang@linux.org.tw>
    Date:   Wed Sep 25 01:16:57 2013 +0800

        android: get rid of HAL pixelformats 5551 and 4444

Cc: "10.1 10.2" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>