selftests: safesetid: Fix Makefile to set correct test program

Fix Makefile to set safesetid-test.sh to TEST_PROGS instead
of non existing run_tests.sh.

Without this fix, I got following error.
----
TAP version 13
1..1
# selftests: safesetid: run_tests.sh
# Warning: file run_tests.sh is missing!
not ok 1 selftests: safesetid: run_tests.sh
----

Fixes: c67e8ec03f3f ("LSM: SafeSetID: add selftest")
Signed-off-by: Masami Hiramatsu <[e-mail]>
Signed-off-by: Shuah Khan <[e-mail]>

tools/testing/selftests/safesetid/Makefile

···
 CFLAGS = -Wall -O2
 LDLIBS = -lcap
 
-TEST_PROGS := run_tests.sh
+TEST_PROGS := safesetid-test.sh
 TEST_GEN_FILES := safesetid-test
 
 include ../lib.mk