ARM: dts: N950: Add wlan support

Add support for the wl1271 wlan chip. As far as I can see N9 uses the
same chip with the same enable and irq gpio, but they use the mmc
interface instead of the spi interface.

Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Tony Lindgren <tony@atomide.com>