We want to use this in another test, so make it available at the top of
the powerpc selftests tree.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

This doesn't really belong in harness.c, it's a helper function. So move
it into utils.c.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>