arm: am57xx: cl-som-am57x: support for FS boot

Supported boot devices are raw QSPI and raw SD card.
Add support for a FAT16/32 file system for SD card.

The SOC's boot ROM only supports FAT file system.
Therefore remove the SPL support for the EXT file system.

Signed-off-by: Uri Mashiach <uri.mashiach@compulab.co.il>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/cl-som-am57x_defconfig b/configs/cl-som-am57x_defconfig
index 8485137..13458da 100644
--- a/configs/cl-som-am57x_defconfig
+++ b/configs/cl-som-am57x_defconfig
@@ -5,6 +5,7 @@
 # CONFIG_SPL_NAND_SUPPORT is not set
 CONFIG_VERSION_VARIABLE=y
 CONFIG_SPL=y
+# CONFIG_SPL_EXT_SUPPORT is not set
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMLS is not set