Kconfig: Migrate FS_FAT / FAT_WRITE

Now that these symbols are in Kconfig, migrate all users.  Use imply on
a number of platforms that default to having this enabled.  As part of
this we must migrate some straglers for CMD_FAT and DOS_PARTITION.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/Kconfig b/arch/Kconfig
index e0e4e84..e447671 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -70,14 +70,15 @@
 	select DM_SPI
 	select DM_GPIO
 	select DM_MMC
-	imply CRC32_VERIFY
 	imply CMD_GETTIME
 	imply CMD_HASH
 	imply CMD_IO
 	imply CMD_IOTRACE
-	imply LZMA
 	imply CMD_LZMADEC
+	imply CRC32_VERIFY
+	imply FAT_WRITE
 	imply HASH_VERIFY
+	imply LZMA
 
 config SH
 	bool "SuperH architecture"