scsi: csiostor: Fix dereference of null pointer rn

scsi: csiostor: Fix dereference of null pointer rn

The error exit path when rn is NULL ends up deferencing the null pointer rn
via the use of the macro CSIO_INC_STATS. Fix this by adding a new error
return path label after the use of the macro to avoid the deference.

Fixes: a3667aaed569 ("[SCSI] csiostor: Chelsio FCoE offload driver")
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://patch.msgid.link/20260129155332.196338-1-colin.i.king@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>