aarch64: Remove old aarch64_expand_sve_vec_cmp_float code

While looking at PR118956, I noticed that we had some dead code
left over after the removal of the vcond patterns.  The can_invert_p
path is no longer used.

gcc/
	* config/aarch64/aarch64-protos.h (aarch64_expand_sve_vec_cmp_float):
	Remove can_invert_p argument and change return type to void.
	* config/aarch64/aarch64.cc (aarch64_expand_sve_vec_cmp_float):
	Likewise.
	* config/aarch64/aarch64-sve.md (vec_cmp<mode><vpred>): Update call
	accordingly.