Makefile: add tools/mkenvimage to target 'clean'

Signed-off-by: Horst Kronstorfer <hkronsto@frequentis.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>

Makefile

@@ -751,7 +751,7 @@ clean:
 	       $(obj)tools/envcrc					  \
 	       $(obj)tools/gdb/{astest,gdbcont,gdbsend}			  \
 	       $(obj)tools/gen_eth_addr    $(obj)tools/img2srec		  \
-	       $(obj)tools/mkimage	   $(obj)tools/mpc86x_clk	  \
+	       $(obj)tools/mk{env,}image   $(obj)tools/mpc86x_clk	  \
 	       $(obj)tools/ncb		   $(obj)tools/ubsha1
 	@rm -f $(obj)board/cray/L1/{bootscript.c,bootscript.image}	  \
 	       $(obj)board/matrix_vision/*/bootscript.img		  \