scsi: zfcp: update width in comment for ZFCP_COMMON_FLAGS mask

v2.6.10 history commit 4062e12b ("[PATCH] s390: zfcp act enhancements")
extended this mask by one nibble with the introduction of
ZFCP_STATUS_COMMON_ACCESS_DENIED == 0x00800000 for ACT (access control
table).
Signed-off-by: Steffen Maier <maier@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/s390/scsi/zfcp_def.h

@@ -49,8 +49,8 @@
 /*************** ADAPTER/PORT/UNIT AND FSF_REQ STATUS FLAGS ******************/
 
 /*
- * Note, the leftmost status byte is common among adapter, port
- * and unit
+ * Note, the leftmost 12 status bits (3 nibbles) are common among adapter, port
+ * and unit. This is a mask for bitwise 'and' with status values.
  */
 #define ZFCP_COMMON_FLAGS			0xfff00000