msm: kgsl: Add support for bulk cache operations

Add a new ioctl, IOCTL_KGSL_GPUMEM_SYNC_CACHE_BULK, which can be used
to sync a number of memory ids at once. This gives the driver an
opportunity to optimize the cache operations based on the total
working set of memory that needs to be managed.

Change-Id: I9693c54cb6f12468b7d9abb0afaef348e631a114
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>