tools: Use exported quiet flag from top-level Makefile

When V is set from the command line, the value is passed to the tools'
Makefiles as well.

Change-Id: I91a1f66de5c1ae6f36b6c9f0a9bd550d4a30f092
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
diff --git a/tools/fiptool/Makefile b/tools/fiptool/Makefile
index ee674b7..5e2ecc1 100644
--- a/tools/fiptool/Makefile
+++ b/tools/fiptool/Makefile
@@ -10,7 +10,7 @@
 
 PROJECT := fiptool${BIN_EXT}
 OBJECTS := fiptool.o tbbr_config.o
-V := 0
+V ?= 0
 
 override CPPFLAGS += -D_GNU_SOURCE -D_XOPEN_SOURCE=700
 CFLAGS := -Wall -Werror -pedantic -std=c99