x86: Add SwapSources

We check register-only source operand to decide if two source operands of
VEX encoded instructions should be swapped.  But source operands in AMX
instructions with two source operands swapped are all register-only
operand.  Add SwapSources to indicate two source operands should be
swapped.

gas/

	* config/tc-i386.c (build_modrm_byte): Check vexswapsources to
	swap two source operands.

opcodes/

	* i386-gen.c (opcode_modifiers): Add VexSwapSources.
	* i386-opc.h (VexSwapSources): New.
	(i386_opcode_modifier): Add vexswapsources.
	* i386-opc.tbl: Add VexSwapSources to BMI2 and BMI instructions
	with two source operands swapped.
	* i386-tbl.h: Regenerated.