vlynq: make whole Kconfig-menu dependant on architecture

This removes an empty menu for most platforms.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>