msm: vidc: Selectively re-allocate ocmem as part of power on

venus_hfi_power_on() is called from various contexts, many of which just
want venus to be clocked (not necessarily active).  So, let the caller
determine if ocmem is to be used or not.

CRs-Fixed: 702822
Change-Id: I1386c2f9adfd26a27ef80c4a56e7dca0f17109b7
Signed-off-by: Deva Ramasubramanian <dramasub@codeaurora.org>