msm: vidc: Load firmware during vidc probe

This change will load the firmware during v4l2 video driver
probe. If there are no active video sessions, then video
hardware will be power collapsed. On targets which can afford
to keep firmware always loaded in memory, this change will help
overcome the delay associated with loading firmware when a new
video session is instantiated.

Change-Id: I4f9981d8db4ff62d652628681bb58fa79ee9b7d4
Signed-off-by: Arun Menon <avmenon@codeaurora.org>