memshare: Add snapshot of memshare driver

The patch is a snapshot of memshare driver taken from msm-4.14 commit
<460b918c8d6d9> (Merge "net: aquantia: support for 32-bit ARM target").

Change-Id: I41c29f5a1c22a294d105cfcbdd6670cbe0bb326a
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>