mhi: core: Handle firmware load through state worker

Upon power up driver queues firmware worker thread if ee is in PBL.
Firmware worker is blocked with a timeout until state worker gets a
chance to run and unblock firmware worker. In case state worker gets a
chance to run after firmware worker timed out results into endpoint
boot up failure. Fix this issue by directly handling firmware loading
from state worker thread.

Change-Id: Id28c5a3eaa3b8075a7eb0185f7e08f21174e1d0d
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>