net: qrtr: mhi: Register for early notifications

Register for status callback to receive fatal error notifications.
Cancel any pending transactions and assume all future transactions
will return immediately with an error.

Early notification can be called from atomic context, change spin_lock
APIs to irqsave/irqrestore variants.

Change-Id: I17ed3a800411eef1bdcaf22c088cb1c9dbd393a6
Signed-off-by: Chris Lew <clew@codeaurora.org>