codec2: C2Store: Integrate C2DmaBufAllocator as a possible allocator

This integrates the C2DmaBufAllocator as one of the possible
allocators for linear allocations, switching its use vs the
ION allocator based on the existance of /dev/ion

Also integrate glue code to handle HAL provided usageMaps for
the C2DmaBufAllocator

Signed-off-by: John Stultz <john.stultz@linaro.org>
Change-Id: Iee2856c0b85d7c5dfe799a2799580a8f69e87d3d