net: core: move mac_pton() to lib/net_utils.c

Since we have at least one user of this function outside of CONFIG_NET
scope, we have to provide this function independently. The proposed
solution is to move it under lib/net_utils.c with corresponding
configuration variable and select wherever it is needed.

Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/lib/Kconfig b/lib/Kconfig
index fe01d41..d246a3b 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -22,6 +22,9 @@
 config GENERIC_STRNLEN_USER
 	bool
 
+config GENERIC_NET_UTILS
+	bool
+
 config GENERIC_FIND_FIRST_BIT
 	bool