msm: vidc: Fix mutex lock deadlock issue

The debugfs method to trigger ssr has already acquired
debugfs srcu lock and is trying to acquire device->lock
in trigger_ssr() function. device->lock was already
acquired by another thread in core_release(). The function
core_release() calling ion_client_destroy() api which is
is trying to acquire the same debugfs srcu lock in function
debugfs_remove_recursive() resulting in deadlock between
trigger_ssr() and core_release() functions. Resolve the 
issue by acquiring core->lock before trigger_ssr() function
to ensure trigger_ssr() and core_release() functions does not
execute at the same time.

CRs-Fixed: 2128555
Change-Id: I35c5c115f0e6281f47a7f108ec75c5870efa743e
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>