arm64: dts: renesas: r8a77990: ebisu: Enable HS400 of SDHI3

Enable HS400 of SDHI3 using the corresponding DT property.
No further changes are required.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>