MIPS: ralink: dts: gardena_smart_gateway_mt7688: Enable WMAC

This patch enables the WMAC controller on the GARDENA smart Gateway and
configures the board specific factory EEPROM setting for this driver.

Signed-off-by: Reto Schneider <reto.schneider@husqvarnagroup.com>
Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Paul Burton <paul.burton@mips.com>
Cc: John Crispin <john@phrozen.org>
Cc: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org