[AArch64, 4/6] Reimplement frsqrts intrinsics

[AArch64, 4/6] Reimplement frsqrts intrinsics

	* config/aarch64/aarch64-builtins.def (rsqrts): New builtins for modes
	VALLF.
	* config/aarch64/aarch64-simd.md (aarch64_rsqrts_<mode>3): Rename to
	"aarch64_rsqrts<mode>".
	* config/aarch64/aarch64.c (get_rsqrts_type): Update gen* name.
	* config/aarch64/arm_neon.h (vrsqrtss_f32): Remove inline assembly.  Use
	builtin.
	(vrsqrtsd_f64): Likewise.
	(vrsqrts_f32): Likewise.
	(vrsqrts_f64): Likewise.
	(vrsqrtsq_f32): Likewise.
	(vrsqrtsq_f64): Likewise.

From-SVN: r237203