Correct CpuMax in i386-opc.h

Correct CpuMax in i386-opc.h

CpuMax should be CpuIntel64, not CpuNo64.  i386-gen.c is updated to
verify that CpuMax is correct.  X86 assembler is updated to properly
set cpuamd64 and cpuintel64.

gas/

	PR gas/20154
	* config/tc-i386.c (intel64): New.
	(cpu_flags_match): Set cpuamd64 and cpuintel64.
	(md_parse_option): Set intel64 instead of cpuamd64 and
	cpuintel64.

opcodes/

	PR gas/20154
	* i386-gen.c (main): Fail if CpuMax is incorrect.
	* i386-opc.h (CpuMax): Set to CpuIntel64.
	* i386-tbl.h: Regenerated.