msm: vidc: Add schedule work functionality to SSR

User can trigger Sub System Restart (SSR) functionality
using command: "echo 1 > /d/msm_vidc/core0/trigger_ssr".
Kernel will acquire debugfs srcu lock before video driver
ssr function is called. There is deadlock if video driver
acquires core lock inside ssr function as other video threads
trying to acquire debugfs srcu lock after core lock acquired.
To resolve the issue schedule a work inside video driver ssr
function and return without acquiring core lock. The SSR
functionality will be executed whenever ssr work handler
is executed by the kernel.

Change-Id: I18f056156ee55dcb16e769e378434ee1ab6c4f5e
Signed-off-by: Maheshwar Ajja <majja@codeaurora.org>