mmc: tmio: bring tuning HW to a sane state with MMC_POWER_OFF

When powering off a card, we need to disable the tuning HW (like SCC for
the Renesas SDHI) to get to a sane state and allow for re-tuning new
cards. This was hidden before because we wrongly did that in hw_reset()
before which was an unintended use of hw_reset(). Now that we corrected
the use of hw_reset() meanwhile, we revealed this shortcoming and need
to fix it properly by explicitly calling the downgrade callback.

Fixes: 6e7d4de1 ("mmc: renesas_sdhi: move wrong 'hw_reset' to 'reset'")
Suggested-by: Takeshi Saito <takeshi.saito.xv@renesas.com>
Reviewed-by: Takeshi Saito <takeshi.saito.xv@renesas.com>
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/20201106072549.1495-3-wsa+renesas@sang-engineering.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>