Makefile: delete file *.itb when make clean

Delete the output file *.itb

Signed-off-by: Randolph <randolph@andestech.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/Makefile b/Makefile
index b204a50..e0040a4 100644
--- a/Makefile
+++ b/Makefile
@@ -2165,7 +2165,7 @@
 	       mkimage-out.spl.mkimage mkimage.spl.mkimage imx-boot.map \
 	       itb.fit.fit itb.fit.itb itb.map spl.map mkimage-out.rom.mkimage \
 	       mkimage.rom.mkimage rom.map simple-bin.map simple-bin-spi.map \
-	       idbloader-spi.img lib/efi_loader/helloworld_efi.S
+	       idbloader-spi.img lib/efi_loader/helloworld_efi.S *.itb
 
 # Directories & files removed with 'make mrproper'
 MRPROPER_DIRS  += include/config include/generated spl tpl vpl \