doc: fix misspellings in include (API docs)

Fix misspellings in .h files missed during code reviews
and affecting generated API documentation

Signed-off-by: David B. Kinder <david.b.kinder@intel.com>

include/net/net_if.h

diff --git a/include/net/net_if.h b/include/net/net_if.h
index 5f05176..7253793 100644
--- a/include/net/net_if.h
+++ b/include/net/net_if.h
@@ -1192,7 +1192,7 @@
  * @brief Go through all the network interfaces and call callback
  * for each interface.
  *
- * @param cb User supplied callback function to call
+ * @param cb User-supplied callback function to call
  * @param user_data User specified data
  */
 void net_if_foreach(net_if_cb_t cb, void *user_data);