pmem: Add fmem call backs

Add callbacks for request/release region to be used with fmem.
These files can be referenced in any board file for use with
any pmem device.

Change-Id: I1a1791bbf8fc00d3e324600aedb5361aa899bc4f
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
2 files changed