msm: vidc: Unset mem core for unused clocks

For a SDM670 SKU, one video core is disabled. The
memory associated with the disable core remains
ON as the associated clock keeps it ON. Set the
clock flags to disable the mem_core for disable
video core.

Change-Id: Ife973b25d247d8b562372c87d7b59f8a583f8365
Signed-off-by: Vikash Garodia <vgarodia@codeaurora.org>