[SCSI] libiscsi: use is_power_of_2

Replacing n & (n - 1) for power of 2 check by is_power_of_2(n)
Signed-off-by: Nvignesh babu <vignesh.babu@wipro.com>
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/libiscsi.c

@@ -24,6 +24,7 @@
 #include <linux/types.h>
 #include <linux/kfifo.h>
 #include <linux/delay.h>
+#include <linux/log2.h>
 #include <asm/unaligned.h>
 #include <net/tcp.h>
 #include <scsi/scsi_cmnd.h>
@@ -1700,7 +1701,7 @@ iscsi_session_setup(struct iscsi_transport *iscsit,
 		qdepth = ISCSI_DEF_CMD_PER_LUN;
 	}
 
-	if (cmds_max < 2 || (cmds_max & (cmds_max - 1)) ||
+	if (!is_power_of_2(cmds_max) ||
 	    cmds_max >= ISCSI_MGMT_ITT_OFFSET) {
 		if (cmds_max != 0)
 			printk(KERN_ERR "iscsi: invalid can_queue of %d. "