[SCSI] qla2xxx: Don't explicitly read mbx registers while processing a system-error.

Callers of qla2x00_async_event() already populate the mb[] array
upon invocation, doing so via the appropriate mailbox register
accessors.  The stale codes removed are leftover-bits kept during
the FWI2 transition.  Though relatively benign, the extra-reads
are not valid for FWI2 boards (ISP24xx and above) and peek into
the incorrect regions of registers.
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/qla2xxx/qla_isr.c

@@ -347,10 +347,6 @@ qla2x00_async_event(scsi_qla_host_t *ha, uint16_t *mb)
 		break;
 
 	case MBA_SYSTEM_ERR:		/* System Error */
-		mb[1] = RD_MAILBOX_REG(ha, reg, 1);
-		mb[2] = RD_MAILBOX_REG(ha, reg, 2);
-		mb[3] = RD_MAILBOX_REG(ha, reg, 3);
-
 		qla_printk(KERN_INFO, ha,
 		    "ISP System Error - mbx1=%xh mbx2=%xh mbx3=%xh.\n",
 		    mb[1], mb[2], mb[3]);