fsi: sbefifo: Use interruptible mutex locking

Some SBE operations have extremely large responses and can require
several minutes to process the response. During this time, the device
lock must be held. If another process attempts an operation, it will
wait for the mutex for longer than the kernel hung task watchdog
allows. Therefore, use the interruptible function to lock the mutex.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210803213016.44739-1-eajames@linux.ibm.com


Signed-off-by: Joel Stanley <joel@jms.id.au>