package/dtc: disable valgrind

Since version 1.5.0, dtc optionally depends on valgrind so disable it by
setting NO_VALGRIND to 1

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/dtc/dtc.mk

@@ -15,11 +15,13 @@ HOST_DTC_DEPENDENCIES = host-bison host-flex
 
 DTC_MAKE_OPTS = \
 	PREFIX=/usr \
-	NO_PYTHON=1
+	NO_PYTHON=1 \
+	NO_VALGRIND=1
 
 HOST_DTC_MAKE_OPTS = \
 	PREFIX=$(HOST_DIR) \
 	NO_PYTHON=1 \
+	NO_VALGRIND=1 \
 	NO_YAML=1
 
 define DTC_POST_INSTALL_TARGET_RM_DTDIFF