powerpc/kprobes: Blacklist emulate_update_regs() from kprobes

Commit 3cdfcbfd

 ("powerpc: Change analyse_instr so it doesn't
modify *regs") introduced emulate_update_regs() to perform part of what
emulate_step() was doing earlier. However, this function was not added
to the kprobes blacklist. Add it so as to prevent it from being probed.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>