[ARM] Add ARMv8.3 VCMLA and VCADD instructions

[ARM] Add ARMv8.3 VCMLA and VCADD instructions

Add support for VCMLA and VCADD advanced SIMD complex number instructions.

The command line option is -march=armv8.3-a+fp16+simd for enabling all
instructions.

In arm-dis.c the formatting syntax was abused a bit to select between
0 vs 90 or 180 vs 270 or 90 vs 270 based on a bit value instead of
duplicating entries in the opcode table.

gas/
	* config/tc-arm.c (do_vcmla, do_vcadd): Define.
	(neon_scalar_for_vcmla): Define.
	(enum operand_parse_code): Add OP_IROT1 and OP_IROT2.
	(NEON_ENC_TAB): Add DDSI and QQSI variants.
	(insns): Add vcmla and vcadd.
	* testsuite/gas/arm/armv8_3-a-simd.d: New.
	* testsuite/gas/arm/armv8_3-a-simd.s: New.
	* testsuite/gas/arm/armv8_3-a-simd-bad.d: New.
	* testsuite/gas/arm/armv8_3-a-simd-bad.l: New.
	* testsuite/gas/arm/armv8_3-a-simd-bad.s: New.

opcodes/
	* arm-dis.c (coprocessor_opcodes): Add vcmla and vcadd.
	(print_insn_coprocessor): Add 'V' format for neon D or Q regs.