Decode DHCP netmask option correctly

Signed-off-by: Chris Dearman <chris@mips.com>
Change-Id: Ibc288458baf2f75c5b19a46e4c97ee59521cc9a5
diff --git a/libnetutils/ifc_utils.c b/libnetutils/ifc_utils.c
index 50095ab..eb33d06 100644
--- a/libnetutils/ifc_utils.c
+++ b/libnetutils/ifc_utils.c
@@ -75,9 +75,8 @@
 
 int ipv4NetmaskToPrefixLength(in_addr_t mask)
 {
-    mask = ntohl(mask);
     int prefixLength = 0;
-    uint32_t m = (uint32_t)mask;
+    uint32_t m = (uint32_t)ntohl(mask);
     while (m & 0x80000000) {
         prefixLength++;
         m = m << 1;
@@ -486,7 +485,7 @@
         if(ioctl(ifc_ctl_sock, SIOCGIFNETMASK, &ifr) < 0) {
             *prefixLength = 0;
         } else {
-            *prefixLength = ipv4NetmaskToPrefixLength((int)
+            *prefixLength = ipv4NetmaskToPrefixLength(
                     ((struct sockaddr_in*) &ifr.ifr_addr)->sin_addr.s_addr);
         }
     }