spl: Kconfig: Replace CONFIG_SPL_FAT_SUPPORT with CONFIG_SPL_FS_FAT

Replace CONFIG_SPL_FAT_SUPPORT with CONFIG_SPL_FS_FAT so
obj-$(CONFIG_$(SPL_)FS_FAT) can be used to control the build in both
SPL and U-Boot.

Signed-off-by: Tien Fong Chee <tien.fong.chee@intel.com>
Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am335x_hs_evm_uart_defconfig b/configs/am335x_hs_evm_uart_defconfig
index e5f54a0..476f006 100644
--- a/configs/am335x_hs_evm_uart_defconfig
+++ b/configs/am335x_hs_evm_uart_defconfig
@@ -6,7 +6,7 @@
 CONFIG_ISW_ENTRY_ADDR=0x40301950
 # CONFIG_SPL_MMC_SUPPORT is not set
 CONFIG_SPL=y
-# CONFIG_SPL_FAT_SUPPORT is not set
+# CONFIG_SPL_FS_FAT is not set
 # CONFIG_SPL_LIBDISK_SUPPORT is not set
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_FIT_IMAGE_POST_PROCESS=y