parisc: fix epoll_pwait syscall on compat kernel

commit ab3e55b119c9653b19ea4edffb86f04db867ac98 upstream.

This bug was detected with the libio-epoll-perl debian package where the
test case IO-Ppoll-compat.t failed.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>