mmc: renesas_sdhi: merge the SCC reset functions

mmc: renesas_sdhi: merge the SCC reset functions

There is no user of renesas_sdhi_reset_scc() anymore, only
renesas_sdhi_disable_scc() so merge these functions into one. I guess
the seperation was cruft anyhow. The BSP doesn't have it anymore and I
can't recall the reason we had it.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20201110162151.37622-3-wsa+renesas@sang-engineering.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>