mmc: sdhci_am654: 'select', not 'depends' REGMAP_MMIO

REGMAP_MMIO is not user-configurable, so we can only satisfy this
dependency by enabling some other Kconfig symbol that properly 'select's
it. Use select like everybody else.

Noticed when trying to enable this driver for compile testing.

Fixes: 59592cc1 ("mmc: sdhci_am654: Add dependency on MMC_SDHCI_AM654")
Signed-off-by: Brian Norris <briannorris@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20221024180300.2292208-1-briannorris@chromium.orgSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/Kconfig

@@ -1075,9 +1075,10 @@ config MMC_SDHCI_OMAP
 
 config MMC_SDHCI_AM654
 	tristate "Support for the SDHCI Controller in TI's AM654 SOCs"
-	depends on MMC_SDHCI_PLTFM && OF && REGMAP_MMIO
+	depends on MMC_SDHCI_PLTFM && OF
 	select MMC_SDHCI_IO_ACCESSORS
 	select MMC_CQHCI
+	select REGMAP_MMIO
 	help
 	  This selects the Secure Digital Host Controller Interface (SDHCI)
 	  support present in TI's AM654 SOCs. The controller supports