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/socfpga_stratix10_defconfig b/configs/socfpga_stratix10_defconfig
index 5f3d733..bc3a3a3 100644
--- a/configs/socfpga_stratix10_defconfig
+++ b/configs/socfpga_stratix10_defconfig
@@ -5,7 +5,7 @@
 CONFIG_TARGET_SOCFPGA_STRATIX10_SOCDK=y
 CONFIG_SPL=y
 CONFIG_IDENT_STRING="socfpga_stratix10"
-CONFIG_SPL_FAT_SUPPORT=y
+CONFIG_SPL_FS_FAT=y
 CONFIG_NR_DRAM_BANKS=1
 CONFIG_BOOTDELAY=5
 CONFIG_SPL_SPI_LOAD=y