mmc: renesas_sdhi_internal_dmac: add R8A77980 to whitelist

I've successfully tested eMMC on R8A77980/Condor. R8A77980 has a single
SDHI core anyway, so can't be a subject of the known RX DMA errata...

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>