msm: camera: reqmgr: Handle schedule request in caller context

Schedule request adds new entry to request table, this call is in
user thread context. Without this change user thread is blocked
till workque processing is finished, this change avoid blocking.

Change-Id: Iacaef51bf4b53d4e5c92d249e47e41cdf603137a
Signed-off-by: Sagar Gore <sgore@codeaurora.org>