mmc: sdhci-pltfm: Rename sdhci_pltfm_register()

Now that sdhci_pltfm_unregister() has been removed, rename
sdhci_pltfm_register() to sdhci_pltfm_init_and_add_host() to better
reflect what it does.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230811130351.7038-17-adrian.hunter@intel.com


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