memshare: Modify the driver to be dynamically loadable

Align memshare driver to be generic kernel image compliant by
modifying the driver to dynamically loadable.

Change-Id: I92bab11f8ff4279b94bd4bce6d17640a3715c26c
Signed-off-by: Manoj Prabhu B <bmanoj@codeaurora.org>