msm: ocmem: Add a separate Kconfig for keeping clocks enabled.

For bringup purposes add a new Kconfig item that performs
the extra vote for the ocmem core clock and thus forcing the
core to remain turned ON at all times.

The previously used Kconfig MSM_OCMEM_POWER_DISABLE for the
same purpose now skips all power operations including clock votes.

Change-Id: I3068dcb84b8caaa900243f5bdffef36c88ff4e5c
Signed-off-by: Naveen Ramaraj <nramaraj@codeaurora.org>