ARM: dts: r8a7790: lager: Enable UHS-I SDR-50

Add the "1v8" pinctrl state and sd-uhs-sdr50 property to SDHI{0,2}.

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>