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/common/spl/spl_sata.c b/common/spl/spl_sata.c
index 12e16d9..aeea793 100644
--- a/common/spl/spl_sata.c
+++ b/common/spl/spl_sata.c
@@ -42,7 +42,7 @@
 #endif
 	err = spl_load_image_fat(stor_dev,
 				CONFIG_SYS_SATA_FAT_BOOT_PARTITION,
-				CONFIG_SPL_FAT_LOAD_PAYLOAD_NAME);
+				CONFIG_SPL_FS_LOAD_PAYLOAD_NAME);
 	if (err) {
 		puts("Error loading sata device\n");
 		hang();