egl/android: Refactor image creation to separate flink and prime paths (v2)

egl/android: Refactor image creation to separate flink and prime paths (v2)

This patch splits current dri2_create_image_android_native_buffer() into
main entry point and two additional functions, one for creating an image
from flink name and one for handling prime FDs using the generic DMA-buf
path. This makes the code cleaner and also prepares for disabling flink
path more easily in the future.

v2: Split into separate patch.
    Add error messages.

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Rob Herring <rob@kernel.org>
Reviewed-by: Chad Versace <chad@kiwitree.net>
Change-Id: Ifdfb5927399d56992fe707160423c29278f49172