aarch64: Remove move_lo/hi_quad expanders

aarch64: Remove move_lo/hi_quad expanders

This patch is the second of two to remove the old
move_lo/hi_quad expanders and move_hi_quad insns.

gcc/
	* config/aarch64/aarch64-simd.md (@aarch64_split_simd_mov<mode>):
	Use aarch64_combine instead of move_lo/hi_quad.  Tabify.
	(move_lo_quad_<mode>, aarch64_simd_move_hi_quad_<mode>): Delete.
	(aarch64_simd_move_hi_quad_be_<mode>, move_hi_quad_<mode>): Delete.
	(vec_pack_trunc_<mode>): Take general_operand elements and use
	aarch64_combine rather than move_lo/hi_quad to combine them.
	(vec_pack_trunc_df): Likewise.