[AArch64, 3/6] Reimplement frsqrte intrinsics

[AArch64, 3/6] Reimplement frsqrte intrinsics

	* config/aarch64/aarch64-builtins.def (rsqrte): New builtins for modes
	VALLF.
	* config/aarch64/aarch64-simd.md (aarch64_rsqrte_<mode>2): Rename to
	"aarch64_rsqrte<mode>".
	* config/aarch64/aarch64.c (get_rsqrte_type): Update gen* name.
	* config/aarch64/arm_neon.h (vrsqrts_f32): Remove inline assembly.  Use
	builtin.
	(vrsqrted_f64): Likewise.
	(vrsqrte_f32): Likewise.
	(vrsqrte_f64): Likewise.
	(vrsqrteq_f32): Likewise.
	(vrsqrteq_f64): Likewise.

From-SVN: r237202