Ensure GL & Gralloc both support FP16 before using it

Change-Id: I3bda750b6011d9a69969fc938a230c2445ee8dae
Merged-In: Id8a53885178d698c7b2fd6fc5ea8d4e36ce2ef15
Fixes: 77973662
Test: builds & CTS passes
1 file changed