msm: vidc: remove sync_lock between get & set session property

Holding sync_lock for the session_get_property and
session_set_property is leading to stability issues
and does not seems to be relevant to hold a sync_lock
here. So, removing it.

CRs-Fixed: 946713
Change-Id: I2333829c7d1938ba7b4a45de38398cfb6cdd36a1
Signed-off-by: Balamurugan Alagarsamy <balaga@codeaurora.org>