add RT5350 wifi support

MTK/Ralink Acked replied and says we can merge this patch under the GPL.

Signed-off-by: Serge Vasilugin <vasilugin@yandex.ru>
Tested-by: Michel Stempin <michel.stempin@wanadoo.fr>
Acked-by: John Crispin <blogic@openwrt.org>

SVN-Revision: 36177