selftests: lib.mk: suppress "cd" output from run_tests target

Suppress "cd" output from run_tests while running tests to declutter the
test results.

Running efivarfs test:
make --silent -C tools/testing/selftests/efivarfs/ run_tests

Before the change:

skip all tests: must be run as root
selftests: efivarfs.sh [PASS]
/lkml/linux-kselftest/tools/testing/selftests/efivarfs

After the change:

skip all tests: must be run as root
selftests: efivarfs.sh [PASS]
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/lib.mk

@@ -18,7 +18,7 @@ define RUN_TESTS
 			echo "selftests: Warning: file $$BASENAME_TEST is not executable, correct this.";\
 			echo "selftests: $$BASENAME_TEST [FAIL]"; \
 		else					\
-			cd `dirname $$TEST`; (./$$BASENAME_TEST && echo "selftests: $$BASENAME_TEST [PASS]") || echo "selftests:  $$BASENAME_TEST [FAIL]"; cd -;\
+			cd `dirname $$TEST` > /dev/null; (./$$BASENAME_TEST && echo "selftests: $$BASENAME_TEST [PASS]") || echo "selftests:  $$BASENAME_TEST [FAIL]"; cd - > /dev/null;\
 		fi;					\
 	done;
 endef