Remove the build error due to ccache.

We have ccache built in CROSS_COMPILE, which mkuboot.sh uses to determin
if the cross-compile mkimage is present. Since ccache is always present,
mkuboot thought the ${CROSS_COMPILE}mkimage is present. Thus the
failure.

Change-Id: Id91c9280583a94fce7354270417562c9cf2a3c53
diff --git a/scripts/mkuboot.sh b/scripts/mkuboot.sh
index 2e3d3cd..d8c0d1a 100755
--- a/scripts/mkuboot.sh
+++ b/scripts/mkuboot.sh
@@ -4,7 +4,7 @@
 # Build U-Boot image when `mkimage' tool is available.
 #
 
-MKIMAGE=$(type -path "${CROSS_COMPILE}mkimage")
+MKIMAGE=$(type -path ${CROSS_COMPILE#*\ }mkimage)
 
 if [ -z "${MKIMAGE}" ]; then
 	MKIMAGE=$(type -path mkimage)