sh: Fix PTRACE_PEEKTEXT/PEEKDATA fallout from generic_ptrace_peekdata().

When generic_ptrace_peekdata() was merged, the break for these cases
ended up getting dropped, which lead to each PEEKTEXT/PEEKDATA op leaking
in to PEEKUSR and get_user_pages() always -EFAULTing. Add the break back
in.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>