powerpc: Update boot wrapper script with the new location of dtc

dtc was moved in 9fffb55f from
arch/powerpc/boot/ to scripts/dtc/

This patch updates the wrapper script to point to the new location of dtc.
Signed-off-by: Lucian Adrian Grijincu <lgrijincu@ixiacom.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/boot/wrapper

@@ -46,6 +46,7 @@ CROSS=
 # directory for object and other files used by this script
 object=arch/powerpc/boot
 objbin=$object
+dtc=scripts/dtc/dtc
 
 # directory for working files
 tmpdir=.
@@ -124,7 +125,7 @@ if [ -n "$dts" ]; then
     if [ -z "$dtb" ]; then
 	dtb="$platform.dtb"
     fi
-    $object/dtc -O dtb -o "$dtb" -b 0 "$dts"
+    $dtc -O dtb -o "$dtb" -b 0 "$dts"
 fi
 
 if [ -z "$kernel" ]; then