powerpc: Emulate icbi, mcrf and conditional-trap instructions

This extends the instruction emulation done by analyse_instr() and
emulate_step() to handle a few more instructions that are found in
the kernel.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --cc arch/powerpc/include/asm/sstep.h
Simple merge

diff --cc arch/powerpc/lib/sstep.c
Simple merge