binman: Allow selection of logging verbosity

Support a new BINMAN_VERBOSE option to the build, to allow passing the
-v flag to binman.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/Makefile b/Makefile
index 9ea602b..b68cbaf 100644
--- a/Makefile
+++ b/Makefile
@@ -1214,7 +1214,8 @@
 quiet_cmd_binman = BINMAN  $@
 cmd_binman = $(srctree)/tools/binman/binman $(if $(BINMAN_DEBUG),-D) \
                 --toolpath $(objtree)/tools \
-                build -u -d u-boot.dtb -O . -m \
+		$(if $(BINMAN_VERBOSE),-v$(BINMAN_VERBOSE)) \
+		build -u -d u-boot.dtb -O . -m \
 		-I . -I $(srctree) -I $(srctree)/board/$(BOARDDIR) \
 		$(BINMAN_$(@F))