rom.sh: unset displaymode on normal initmode

Otherwise, you get "normal_normal" in the image name.

Signed-off-by: Leah Rowe <leah@libreboot.org>

include/rom.sh

@@ -92,6 +92,7 @@ mkcorebootbin()
 	$dry x_ cp "$srcdir/build/coreboot.rom" "$tmprom"
 
 	initmode="${defconfig##*/}"; displaymode="${initmode##*_}"
+	[ "$displaymode" = "$initmode" ] && displaymode="" # "normal" config
 	initmode="${initmode%%_*}"
 	cbfstool="elf/cbfstool/$tree/cbfstool"