msm: vidc: avoid repeated calls to handle_sys_error

There is no need to call handle_sys_error if it is
called already. So check the core state to return
if it is not in valid state.

CRs-Fixed: 1072500

Change-Id: Iaa77ea31f29190dcf35b4bfc4913b8eec0d638b0
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>