selftests/powerpc: Use the test harness for the TM DSCR test

This gives us standardised success/failure output and also handles
killing the test if it runs forever (2 minutes).

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --cc tools/testing/selftests/powerpc/tm/Makefile
Simple merge

diff --cc tools/testing/selftests/powerpc/tm/tm-resched-dscr.c
Simple merge