Fixed the variable types in inet_ntoa() to comply with API change.
diff --git a/src/core/inet.c b/src/core/inet.c
index 694cb00..4133d51 100644
--- a/src/core/inet.c
+++ b/src/core/inet.c
@@ -302,11 +302,11 @@
  */
 char *inet_ntoa(struct in_addr addr)
 {
-  static u8_t str[16];
+  static char str[16];
   u32_t s_addr = addr.s_addr;
-  u8_t inv[3];
-  u8_t *rp;
-  u8_t *ap;
+  char inv[3];
+  char *rp;
+  char *ap;
   u8_t rem;
   u8_t n;
   u8_t i;