uio: msm_sharedmem: shared memory region access is also given to vm-nav

If vm-nav-path dtsi property is set, then the shared memory region will
be given access to vm-nav-path also.

Change-Id: I0aef894dbee78c2e3d7d67f61a238a889050037a
Signed-off-by: Sridhar Arra <sarra@codeaurora.org>