scsi: target: pscsi: Clean up after failure in pscsi_map_sg()

stable inclusion
from stable-5.10.29
commit 47f8bc68ae956afdb1e0a36b5981f2f7d0b1db1d
bugzilla: 51789

--------------------------------

[ Upstream commit 36fa766f ]

If pscsi_map_sg() fails, make sure to drop references to already allocated
bios.

Link: https://lore.kernel.org/r/20210323212431.15306-2-mwilck@suse.com


Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by:   Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>