kbuild: use shorten logs for mkimage rules

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/arch/arm/cpu/armv7/omap4/config.mk b/arch/arm/cpu/armv7/omap4/config.mk
index 2a3d1c5..ad44d63 100644
--- a/arch/arm/cpu/armv7/omap4/config.mk
+++ b/arch/arm/cpu/armv7/omap4/config.mk
@@ -9,7 +9,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 ifdef CONFIG_SPL_BUILD
-ALL-y	+= $(OBJTREE)/MLO
+ALL-y	+= MLO
 else
 ALL-y	+= u-boot.img
 endif