powerpc: Use get_signal() signal_setup_done()

Use the more generic functions get_signal() signal_setup_done()
for signal delivery.
This inverts also the return codes of setup_*frame() to follow the
kernel convention.

Signed-off-by: Richard Weinberger <richard@nod.at>

diff --cc arch/powerpc/kernel/signal.c
Simple merge

diff --cc arch/powerpc/kernel/signal.h
Simple merge

diff --cc arch/powerpc/kernel/signal_32.c
Simple merge

diff --cc arch/powerpc/kernel/signal_64.c
Simple merge