mmc: sdhci-uhs2: add add_host() and others to set up the driver

This is a UHS-II version of sdhci's add_host/remove_host operation.
Any sdhci drivers which are capable of handling UHS-II cards must
call those functions instead of the corresponding sdhci's.

Signed-off-by: Ben Chuang <ben.chuang@genesyslogic.com.tw>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Victor Shih <victor.shih@genesyslogic.com.tw>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Message-ID: <20241018105333.4569-9-victorshihgli@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>