msm: camera: reqmgr: Remove mem_mgr init & deinit calls

Remove the calls to init & deinit the mem_mgr as part of
driver probe and remove. The init & deinit is already
being done as part of open & release v4l2 file ops.

Change-Id: Ic97cb8b628f3406d88b21d914cd7b4f64b9d833c
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>