Convert CONFIG_SPL_MMC_SUPPORT to Kconfig

Move this option to Kconfig and tidy up existing uses.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/armv7/omap3/Kconfig b/arch/arm/cpu/armv7/omap3/Kconfig
index 5cf21c0..48b596a 100644
--- a/arch/arm/cpu/armv7/omap3/Kconfig
+++ b/arch/arm/cpu/armv7/omap3/Kconfig
@@ -21,6 +21,9 @@
 config SPL_LIBGENERIC_SUPPORT
 	default y
 
+config SPL_MMC_SUPPORT
+	default y
+
 choice
 	prompt "OMAP3 board select"
 	optional
diff --git a/arch/arm/cpu/armv7/omap4/Kconfig b/arch/arm/cpu/armv7/omap4/Kconfig
index e83ef2e..b92220a 100644
--- a/arch/arm/cpu/armv7/omap4/Kconfig
+++ b/arch/arm/cpu/armv7/omap4/Kconfig
@@ -21,6 +21,9 @@
 config SPL_LIBGENERIC_SUPPORT
 	default y
 
+config SPL_MMC_SUPPORT
+	default y
+
 choice
 	prompt "OMAP4 board select"
 	optional
diff --git a/arch/arm/cpu/armv7/omap5/Kconfig b/arch/arm/cpu/armv7/omap5/Kconfig
index ff9ad6e..e74a867 100644
--- a/arch/arm/cpu/armv7/omap5/Kconfig
+++ b/arch/arm/cpu/armv7/omap5/Kconfig
@@ -21,6 +21,9 @@
 config SPL_LIBGENERIC_SUPPORT
 	default y
 
+config SPL_MMC_SUPPORT
+	default y
+
 choice
 	prompt "OMAP5 board select"
 	optional
diff --git a/arch/arm/cpu/armv8/zynqmp/Kconfig b/arch/arm/cpu/armv8/zynqmp/Kconfig
index f7ab9c0..0e055e2 100644
--- a/arch/arm/cpu/armv8/zynqmp/Kconfig
+++ b/arch/arm/cpu/armv8/zynqmp/Kconfig
@@ -12,6 +12,9 @@
 config SPL_LIBGENERIC_SUPPORT
 	default y
 
+config SPL_MMC_SUPPORT
+	default y
+
 config SYS_BOARD
 	default "zynqmp"