ARM: dts: microchip: sama7d65: Force SDMMC Legacy mode

ARM: dts: microchip: sama7d65: Force SDMMC Legacy mode

The SDMMC in this IP currently only supports legacy mode
due to a hardware quirk, setting the flags to reflect the limitation.

Fixes: deaa14ab6b06 ("ARM: dts: microchip: add support for sama7d65_curiosity board")
Signed-off-by: Ryan Wanner <Ryan.Wanner@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20250819170528.126010-1-Ryan.Wanner@microchip.com
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>