mmc: renesas_sdhi: Add r8a7743/5 support

Add support for r8a7743/5 SoC. Renesas RZ/G1[ME] (R8A7743/5) SDHI
is identical to the R-Car Gen2 family.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>