Return the actual error code in __scsi_execute() (which, according to the
documentation, should have happened anyway).  And audit all callers to cope
with negative return values from __scsi_execute() and friends.

[mkp: resolve conflict and return bool]

Link: https://lore.kernel.org/r/20210427083046.31620-7-hare@suse.deReviewed-by: NBart Van Assche <bvanassche@acm.org>
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NHannes Reinecke <hare@suse.de>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>