The GRALLOC_USAGE_PROTECTED flag that was used
earlier for content protection is also used for
some other use cases such as disabling of
screen captures. Define this new flag that
is explicitly used for allocating secured
buffers for DRM.
Change-Id: Ia33f79fa0dea7f2f16dd320f267203e6173af48e
CRs-fixed: 348454
(cherry picked from commit 440a996f13be732895524412762793f109681c11)