[PATCH] powerpc/kprobes: fix singlestep out-of-line

We currently single-step inline if the instruction on which a kprobe is
inserted is a trap variant.

- variants (such as tdnei, used by BUG()) typically evaluate a condition
  and cause a trap only if the condition is satisfied.
- kprobes uses the unconditional "trap" (0x7fe00008) and single-stepping
  again on this instruction, resulting in another trap without
  evaluating the condition is obviously incorrect.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>