srp_free_req() uses the scsi_cmnd structure contents to unmap
buffers, so we must invoke srp_free_req() before we release
ownership of that structure.
Signed-off-by: Bart Van Assche <bvanassche@acm.org> Acked-by: David Dillow <dillowda@ornl.gov> Signed-off-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>