parisc: Add HAVE_REGS_AND_STACK_ACCESS_API feature

Some parts of the HAVE_REGS_AND_STACK_ACCESS_API feature is needed for
the rseq syscall. This patch adds the most important parts, and as long
as we don't support kprobes, we should be fine.

Signed-off-by: Helge Deller <deller@gmx.de>