mmc: renesas_sdhi_internal_dmac: Fix DMA buffer alignment from 8 to 128-bytes

According to the latest datasheet, the internal DMAC buffer alignment
R-Car Gen3 SDHI HW should be 128-bytes. So, fix it.

Signed-off-by: Takeshi Saito <takeshi.saito.xv@renesas.com>
[shimoda: revise commit description, rebase]
Fixes: 2a68ea78

 ("mmc: renesas-sdhi: add support for R-Car Gen3 SDHI DMAC")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/1608114572-1892-2-git-send-email-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>