scsi: qla1280: Remove redundant assignment to variable 'mr'

The variable 'mr' being assigned a value that is never read, the assignment
is redundant and can be removed.

Cleans up clang scan build warning:

drivers/scsi/qla1280.c:2481:2: warning: Value stored to 'mr' is never
read [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20240215153533.2067413-1-colin.i.king@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>