Rename some defines containing FAT in their name to be filesystem generic

Rename some defines containing FAT in their name to be filesystem generic:
MMCSD_MODE_FAT => MMCSD_MODE_FS
CONFIG_SPL_FAT_LOAD_ARGS_NAME => CONFIG_SPL_FS_LOAD_ARGS_NAME
CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME => CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
CONFIG_SYS_MMC_SD_FAT_BOOT_PARTITION => CONFIG_SYS_MMC_SD_FS_BOOT_PARTITION

Signed-off-by: Guillaume GARDET <guillaume.gardet@free.fr>
Cc: Tom Rini <trini@ti.com>
diff --git a/arch/arm/cpu/armv7/zynq/spl.c b/arch/arm/cpu/armv7/zynq/spl.c
index 9ff2ef2..31627f9 100644
--- a/arch/arm/cpu/armv7/zynq/spl.c
+++ b/arch/arm/cpu/armv7/zynq/spl.c
@@ -63,7 +63,7 @@
 #ifdef CONFIG_SPL_MMC_SUPPORT
 u32 spl_boot_mode(void)
 {
-	return MMCSD_MODE_FAT;
+	return MMCSD_MODE_FS;
 }
 #endif