drm_hwcomposer: Add LCD panel support

This patch adds support for LCD panels (am57xevm, am65 boards)
to be recognized as internal displays. Without this support
no picture can be seen on LCD panels because of SurfaceFlinger crash.

Signed-off-by: Mykhailo Sopiha <mykhailo.sopiha@linaro.org>
Change-Id: I6720a9386b31151b528c08de578b4c695e649b28