arm64: dts: imx8mp-verdin: drop limit to sdio wi-fi frequency to 100 mhz

SDIO frequency was limited to workaround some instabilities, however it
turned out that the instability had nothing to do with the speed but was
because of an issue with the USDHC IP that was fixed in
commit 52e4c32b ("mmc: sdhci-esdhc-imx: only enable DAT[0] and CMD line
auto tuning for SDIO device").

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: João Paulo Gonçalves <joao.goncalves@toradex.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>