msm: move ocmem to its new location

According to the new guidelines, ocmem should be
located within drivers/soc/msm, and since there are quite
a few ocmem source files, they have been moved into
an ocmem subdirectory.
Also, the header file which should be visible to
other subsystems (ocmem.h) has been moved to include/soc/msm

Change-Id: Ic735520759f26911802f0ac68a24dc2f9150b0a0
Signed-off-by: Neeti Desai <neetid@codeaurora.org>