[SCSI] zfcp: Use correct width for timer_interval field

The timer_interval is 14 bits in width. Introduce a define for
properly masking the value.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index 71663fb..ee0c1df 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -495,7 +495,7 @@
 	fc_host_supported_classes(shost) = FC_COS_CLASS2 | FC_COS_CLASS3;
 
 	adapter->hydra_version = bottom->adapter_type;
-	adapter->timer_ticks = bottom->timer_interval;
+	adapter->timer_ticks = bottom->timer_interval & ZFCP_FSF_TIMER_INT_MASK;
 	adapter->stat_read_buf_num = max(bottom->status_read_buf_num,
 					 (u16)FSF_STATUS_READS_RECOM);