When kzalloc() returns NULL, no error return code of mpt3sas_base_attach()
is assigned. To fix this bug, r is assigned with -ENOMEM in this case.

Link: https://lore.kernel.org/r/20210308035241.3288-1-baijiaju1990@gmail.com
Fixes: c696f7b8 ("scsi: mpt3sas: Implement device_remove_in_progress check in IOCTL path")
Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>