fs: fat: add kbuild configuration support

Add Kconfig symbols for various configurations
supported by FAT filesystem support code.

CONFIG_SUPPORT_VFAT has been left out since its
force enabled in include/fat.h and probably
should get removed at some point.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
[trini: add select FS_FAT for CMD_FAT and SPL_FAT_SUPPORT]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/common/spl/Kconfig b/common/spl/Kconfig
index eabb2d0..48a0fad 100644
--- a/common/spl/Kconfig
+++ b/common/spl/Kconfig
@@ -306,6 +306,7 @@
 config SPL_FAT_SUPPORT
 	bool "Support FAT filesystems"
 	depends on SPL
+	select FS_FAT
 	help
 	  Enable support for FAT and VFAT filesystems with SPL. This
 	  permits U-Boot (or Linux in Falcon mode) to be loaded from a FAT