mmc: sdhci-of-aspeed: Configure the SDHCIs as specified by the devicetree.

The hardware provides capability configuration registers for each SDHCI
in the global configuration space for the SD controller. Writes to the
global capability registers are mirrored to the capability registers in
the associated SDHCI. Configuration of the capabilities must be written
through the mirror registers prior to initialisation of the SDHCI.

Signed-off-by: Steven Lee <steven_lee@aspeedtech.com>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210524073308.9328-5-steven_lee@aspeedtech.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>