soong_config: Allow extension of valid gralloc 1.0 buffer usage bits

* fw/native change I7f4174581e24e361577640b9263514a168ed482d
  implemented validation of the buffer description info prior to
  creating the descriptor. Some of our legacy devices need to
  whitelist additional usage bits to support various functionality.
* The TARGET_ADDITIONAL_GRALLOC_10_USAGE_BITS variable can contain
  a singular roll-up value (e.g., 0x02000000U), a left-shifted bit
  (e.g., (1 << 25)), a bitwise OR of these things, or essentially
  anything that the compiler can choke down.

Change-Id: I2127d33b03426b5e0f981aae837e07d82163fa17