mmc: renesas-sdhi: add support for R-Car Gen3 SDHI DMAC

Add a new variant of the SDHI driver to support R-Car Gen3 with DMA via
on-chip bus mastering.  Since the DMAC is in a part of the SDHI module it
is not suitable to be used via DMA Engine.

Clearing of DM_CM_INFO1 after DMA thanks to Dirk Behme

Cc: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Ai Kyuse <ai.kyuse.uw@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>