msm: vidc: Delete core from driver list before free

When unbind is called core is freed but its entry
from driver core list is not removed, as a result
driver list still has stale addresses. If now bind
is called, new core gets added to driver core list
then list_add sanity checks fails because of stale
address in the list.
Fix is to remove the core list entry from driver
core list when core is freed, so that there are
no stale entries.

Change-Id: I5504f8aeaf2a1fc1f714b05683b9546c094b2726
Signed-off-by: SaiVamshi Dobbali <sdobbali@codeaurora.org>