gdbarch software_single_step frame_info to regcache: rs6000

gdbarch software_single_step frame_info to regcache: rs6000

gdb:

2016-11-22  Yao Qi  <yao.qi@linaro.org>

	* rs6000-aix-tdep.c (branch_dest): Replace parameter frame with
	regcache.  Call get_regcache_arch instead of get_frame_arch.
	Call regcache_raw_get_unsigned instead of
	get_frame_register_unsigned.
	(rs6000_software_single_step): Likewise.
	* rs6000-tdep.c (ppc_deal_with_atomic_sequence): Call
	get_regcache_arch instead of get_frame_arch.  Call
	regcache_read_pc instead of get_frame_pc.