mmc: move MMC_SDHCI_IO_ACCESSORS to Kconfig

This is a user-unconfigurable option that is selected by the
drivers that need to overwrite SDHCI IO memory accessors.
(BCM2835 SDHCI seems the only driver that needs to do so.)
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NTom Rini <trini@konsulko.com>
Reviewed-by: NJaehoon Chung <jh80.chung@samsung.com>

drivers/mmc/Kconfig

@@ -132,6 +132,13 @@ config MMC_SDHCI
 
 	  If unsure, say N.
 
+config MMC_SDHCI_IO_ACCESSORS
+	bool
+	depends on MMC_SDHCI
+	help
+	  This is silent Kconfig symbol that is selected by the drivers that
+	  need to overwrite SDHCI IO memory accessors.
+
 config MMC_SDHCI_SDMA
 	bool "Support SDHCI SDMA"
 	depends on MMC_SDHCI
@@ -143,6 +150,7 @@ config MMC_SDHCI_BCM2835
 	tristate "SDHCI support for the BCM2835 SD/MMC Controller"
 	depends on ARCH_BCM283X
 	depends on MMC_SDHCI
+	select MMC_SDHCI_IO_ACCESSORS
 	help
 	  This selects the BCM2835 SD/MMC controller.
 

include/configs/rpi.h

@@ -83,7 +83,6 @@
 
 /* SD/MMC configuration */
 #define CONFIG_GENERIC_MMC
-#define CONFIG_MMC_SDHCI_IO_ACCESSORS
 
 #ifdef CONFIG_CMD_USB
 #define CONFIG_USB_DWC2