aarch64: Add support for unpacked SVE FP binary arithmetic

aarch64: Add support for unpacked SVE FP binary arithmetic

This patch extends the expanders for unpredicated smax, smin, add, sub,
mul, min, and max, so that they support partial SVE FP modes.

The relevant insn and splitting patterns are also updated.

gcc/ChangeLog:

	* config/aarch64/aarch64-sve.md (<optab><mode>3): Extend from
	SVE_FULL_F to SVE_F, use aarch64_sve_fp_pred.
	(*post_ra_<sve_fp_op><mode>3): Extend from SVE_FULL_F to SVE_F.
	(@aarch64_pred_<optab><mode>): Extend from SVE_FULL_F to SVE_F,
	use aarch64_predicate_operand (ADD/SUB/MUL/MAX/MIN).
	(split for using unpredicated insns): Move SVE_RELAXED_GP into
	the pattern, rather than testing for it in the condition.
	* config/aarch64/aarch64-sve2.md (@aarch64_pred_<optab><mode>):
	Extend from VNx8BF_ONLY to SVE_BF.

gcc/testsuite/ChangeLog:

	* g++.target/aarch64/sve/unpacked_binary_bf16_1.C: New test.
	* g++.target/aarch64/sve/unpacked_binary_bf16_2.C: Likewise.
	* gcc.target/aarch64/sve/unpacked_builtin_fmax_1.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_builtin_fmax_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_builtin_fmin_1.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_builtin_fmin_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fadd_1.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fadd_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fmaxnm_1.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fmaxnm_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fminnm_1.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fminnm_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fmul_1.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fmul_2.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fsubr_1.c: Likewise.
	* gcc.target/aarch64/sve/unpacked_fsubr_2.c: Likewise.