(ppc_arch): Check for PPC_OPCODE_PPC before PPC_OPCODE_POWER. (md_begin): If an instruction has a size specific flag set, only add it if we are assembling that size.
* config/tc-ppc.c (md_parse_option): Add -mpwrx (POWER/2 aka RIOS2), -mpwr (POWER aka RIOS1), -mppc (PowerPC aka MPC603/604), and -many (all architectures).