msm: vidc: replace resurrect_fw with unload_fw

resurrect_fw() unloads and reloads firmware after 5 seconds.
Opening new sessions during these 5 seconds fails. This
commit replaces resurrect_fw() with unload_fw ensuring current
session is unloaded cleanly.

Change-Id: Iaffc7b0e752f488182cd15db2913742416d3662d
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>
Signed-off-by: Arun Menon <avmenon@codeaurora.org>