core: Add bt_str2ba() to bluetooth.h

This patch adds a utility Bluetooth function to convert Bluetooth
address from string to bdaddr_t.

src/bluetooth.h

@@ -69,3 +69,11 @@ static inline int bt_bacmp(const bdaddr_t *ba1, const bdaddr_t *ba2)
 {
 	return memcmp(ba1, ba2, sizeof(bdaddr_t));
 }
+
+static inline void bt_str2ba(const char *str, bdaddr_t *ba)
+{
+	int i;
+
+	for (i = 5; i >= 0; i--, str += 3)
+		ba->b[i] = strtol(str, NULL, 16);
+}

src/handsfree-audio.c

@@ -26,6 +26,7 @@
 #include <errno.h>
 #include <stdio.h>
 #include <stdint.h>
+#include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>