ARM: dts: imx7-colibri: disable HS400

Force HS200 by masking bit 63 of the SDHCI capability register.
The i.MX ESDHC driver uses SDHCI_QUIRK2_CAPS_BIT63_FOR_HS400. With
that the stack checks bit 63 to descide whether HS400 is available.
Using sdhci-caps-mask allows to mask bit 63. The stack then selects
HS200 as operating mode.

This prevents rare communication errors with minimal effect on
performance:
	sdhci-esdhc-imx 30b60000.usdhc: warning! HS400 strobe DLL
		status REF not lock!

Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>