mmc: sdhci-of-dwcmshc: add dwcmshc_pltfm_data

Abstract dwcmshc_pltfm_data to hold the sdhci_pltfm_data
plus some comoon operations of soc such as init/postinit.

Signed-off-by: Chen Wang <unicorn_wang@outlook.com>
Tested-by: Drew Fustini <drew@pdp7.com> # TH1520
Tested-by: Inochi Amaoto <inochiama@outlook.com> # Duo and Huashan Pi
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/cb2c68c594286e9588c53acb76163e60c140c02b.1722847198.git.unicorn_wang@outlook.com


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