Add support for yet some more new ISA 3.0 instructions.

Add support for yet some more new ISA 3.0 instructions.

opcodes/
	* ppc-opc.c (RM, DRM, VXASH, VXASH_MASK, XMMF, XMMF_MASK): New defines.
	(powerpc_opcodes) <brd, brh, brw, mffsce, mffscdrn, mffscdrni,
	mffscrn, mffscrni, mffsl, nandxor, rldixor, setbool,
	xor3>: New mnemonics.
	<setb>: Change to a VX form instruction.
	(insert_sh6): Add support for rldixor.
	(extract_sh6): Likewise.

gas/
	* testsuite/gas/ppc/power9.d <brd, brh, brw, mffs, mffs., mffsce,
	mffscdrn, mffscdrni, mffscrn, mffscrni, mffsl, nandxor, rldixor,
	setbool, xor3>: New tests.
	* testsuite/gas/ppc/power9.s: Likewise.