msm: Add bindings for memory reservations

To get large contiguous memory allocations, a dedicated carved out
memory pool is created. The size of this pool is determined by the
sizes declared by devices. Add size bindings so drivers can increase
the size needed for reservations. Also add bindings to allow drivers
to reserve memory with memblock_reserve to reserve specific memory
regions.

Change-Id: Icc51aef5069a7964c03c5c52f24e40b96f4b2781
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>