mmc: core: Drop HS400 caps unless 8-bit bus is supported too

When mmc_select_hs400es() tries to switch to the HS400 ES mode, it may bail
out early if the host doesn't support an 8-bit buswidth, as it's required
for the HS400 mode.

To improve the situation, let's instead drop the HS400 bits from the
capability field if the 8-bit bus isn't supported. In this way, we allow
the mmc initialization to continue by trying a lower speed mode.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20220303165151.129806-1-ulf.hansson@linaro.org