selftests/powerpc: Add missing newline at end of file

"git diff" says:

    \ No newline at end of file

after modifying the file.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[mpe: Rebase since addition of another test]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>