Wifi chip description, which causes the following schema warning:

imx6q-prti6q.dtb: mmc@2194000: Unevaluated properties are not allowed ('wifi' was unexpected)

Pass the missing items to fix it.
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>