Convert CONFIG_SPL_FAT_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 85ea140..de65ac6 100644
--- a/arch/arm/cpu/armv7/omap3/Kconfig
+++ b/arch/arm/cpu/armv7/omap3/Kconfig
@@ -3,6 +3,9 @@
 config SPL_EXT_SUPPORT
 	default y
 
+config SPL_FAT_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 6a05625..92eb2f4 100644
--- a/arch/arm/cpu/armv7/omap4/Kconfig
+++ b/arch/arm/cpu/armv7/omap4/Kconfig
@@ -3,6 +3,9 @@
 config SPL_EXT_SUPPORT
 	default y
 
+config SPL_FAT_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 5460d7a..e367828 100644
--- a/arch/arm/cpu/armv7/omap5/Kconfig
+++ b/arch/arm/cpu/armv7/omap5/Kconfig
@@ -3,6 +3,9 @@
 config SPL_EXT_SUPPORT
 	default y
 
+config SPL_FAT_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 ed3305d..a049fad 100644
--- a/arch/arm/cpu/armv8/zynqmp/Kconfig
+++ b/arch/arm/cpu/armv8/zynqmp/Kconfig
@@ -1,5 +1,8 @@
 if ARCH_ZYNQMP
 
+config SPL_FAT_SUPPORT
+	default y
+
 config SYS_BOARD
 	default "zynqmp"
 
diff --git a/arch/arm/mach-zynq/Kconfig b/arch/arm/mach-zynq/Kconfig
index a982320..2ed8e98 100644
--- a/arch/arm/mach-zynq/Kconfig
+++ b/arch/arm/mach-zynq/Kconfig
@@ -1,5 +1,8 @@
 if ARCH_ZYNQ
 
+config SPL_FAT_SUPPORT
+	default y
+
 config SYS_BOARD
 	default "zynq"