dfu: Rename _FUNCTION_DFU to DFU_OVER_

Do the following to make the symbol names less confusing.

sed -i "s/\([TU][^_]\+\)_FUNCTION_DFU/DFU_OVER_\1/g" \
	`git grep _FUNCTION_DFU | cut -d ":" -f 1 | sort -u`

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Lukasz Majewski <lukma@denx.de>
diff --git a/README b/README
index fabd532..48db0cb 100644
--- a/README
+++ b/README
@@ -1198,7 +1198,7 @@
 		key for the Replay Protection Memory Block partition in eMMC.
 
 - USB Device Firmware Update (DFU) class support:
-		CONFIG_USB_FUNCTION_DFU
+		CONFIG_DFU_OVER_USB
 		This enables the USB portion of the DFU USB class
 
 		CONFIG_DFU_MMC