Remove unnecessary use of export

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
diff --git a/tests/scripts/quiet/make b/tests/scripts/quiet/make
index 6af3a57..920e5b8 100755
--- a/tests/scripts/quiet/make
+++ b/tests/scripts/quiet/make
@@ -12,8 +12,8 @@
 # export VERBOSE_LOGS=1
 
 # don't silence invocations containing these arguments
-export NO_SILENCE=" --version | test "
+NO_SILENCE=" --version | test "
 
-export TOOL="make"
+TOOL="make"
 
 . "$(dirname "$0")/quiet.sh"