selftests/powerpc: Skip tm-trap if transactional memory is not enabled

Some processor revisions do not support transactional memory, and
additionally kernel support can be disabled. In either case the
tm-trap test should be skipped, otherwise it will fail with a SIGILL.

Fixes: a08082f8e4 ("powerpc/selftests: Check endianness on trap in TM")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/tm/tm-trap.c

@@ -255,6 +255,8 @@ int tm_trap_test(void)
 
 	struct sigaction trap_sa;
 
+	SKIP_IF(!have_htm());
+
 	trap_sa.sa_flags = SA_SIGINFO;
 	trap_sa.sa_sigaction = trap_signal_handler;
 	sigaction(SIGTRAP, &trap_sa, NULL);