qcom: Mark some gralloc bits as valid

 * Add GRALLOC_USAGE_PRIVATE_WFD as valid gralloc bits for all
   the platforms and GRALLOC_USAGE_PRIVATE_10BIT_TP only for the
   UM 4.9-based platforms. Both are defined in the respective
   display HALs (in gralloc/gralloc_priv.h) being the latter
   only available for sdm845.

 * This results in the same as applying https://goo.gl/SR7sFY,
   but it's preferable since it makes use of our own method of
   extending the valid gralloc 1.0 usage bits (see commit 59009f8a).
   TARGET_ADDITIONAL_GRALLOC_10_USAGE_BITS is extended here on
   purpose and as a bitwise OR of all the values in order not to
   clear what might have been set in the device trees.

Change-Id: I5536f341e75088cc72ac369065011388f0a6d3f1