selftests: exec: revert to default emit rule

With the previous patch, the installation method change from install
to rsync. There is no need to create subdir during test, the
default EMIT_TESTS is enough.

This patch essentially revert commit 84cbd9e4 ("selftests/exec: do not
install subdir as it is already created").
Suggested-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NBamvor Jian Zhang <bamvor.zhangjian@linaro.org>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/exec/Makefile

 CFLAGS = -Wall
 BINARIES = execveat
-DEPS = execveat.symlink execveat.denatured script
+DEPS = execveat.symlink execveat.denatured script subdir
 all: $(BINARIES) $(DEPS)
 
 subdir:
@@ -22,7 +22,5 @@ TEST_FILES := $(DEPS)
 
 include ../lib.mk
 
-override EMIT_TESTS := echo "mkdir -p subdir; (./execveat && echo \"selftests: execveat [PASS]\") || echo \"selftests: execveat [FAIL]\""
-
 clean:
 	rm -rf $(BINARIES) $(DEPS) subdir.moved execveat.moved xxxxx*