[SVE][AArch64] Refine hasSVEArgsOrReturn

As described in aapcs64 (https://github.com/ARM-software/abi-aa/blob/2022Q1/aapcs64/aapcs64.rst#scalable-vector-registers)
AAVPCS is used only when registers z0-z7 take an SVE argument. This fixes the case where floats occupy the lower bits
of registers z0-z7 but SVE arguments in registers greater than z7 cause a function to use AAVPCS where it should use AAPCS.

Moving SVE function deduction from AArch64RegisterInfo::hasSVEArgsOrReturn to AArch64TargetLowering::LowerFormalArguments
where physical register lowering is more accurate fixes this.

Differential Revision: https://reviews.llvm.org/D127209