Minor changes required to port kprobes for sparc64.

- arch_prepare_kprobe() returns an integer.

- added arch_remove_kprobe().

- changes to access copy of original instruction, since kprobe_opcode_t
  insn[MAX_INSN_SIZE] is moved from struct kprobe to a struct
  arch_specific_insn.
Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>