Gralloc: Move GRALLOC_USAGE_PRIVATE_ALLOC_UBWC_PI to lower 32 bits

1) Move GRALLOC_USAGE_PRIVATE_ALLOC_UBWC_PI to bit 30. Custom formats
like HAL_PIXEL_FORMAT_YCbCr_420_P010_VENUS and
HAL_PIXEL_FORMAT_YCbCr_420_TP10_UBWC can now be used directly without
needing gralloc flags to be set therby freeing bit 27 and bit 30.
2) Add PRIV_FLAGS_SECURE_BUFFER and PRIV_FLAGS_USES_ION to
GetCustomFormatFlags API.

Change-Id: Iee14af2f1a3774ef9922aa380c204ca5ebf60147
CRs-Fixed: 2255171
2 files changed