ARM: dts: imx7d-smegw01: Fix the SDIO description

usdhc2 is connected to a Wifi chip that is powered by a 3.3V supply.

Pass the "no-1-8-v" property to guarantee that no communication is
made at 1.8V.

While at it, also remove the unnecessary properties: "cap-sd-highspeed",
"sd-uhs-ddr50", and "mmc-ddr-1_8v".

Fixes: 9ac0ae97 ("ARM: dts: imx7d-smegw01: Add support for i.MX7D SMEGW01 board")
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>