[AArch64][SME2] Fix SME2 mla/mls tests (#76711)

The ACLE defines these builtins as svmla[_single]_za32[_f32]_vg1x2,
which means the SVE_ACLE_FUNC macro should test the overloaded forms as

SVE_ACLE_FUNC(svmla,_single,_za32,_f32,_vg1x2)


https://github.com/ARM-software/acle/blob/b88cbf7e9c104100bb5016c848763171494dee44/main/acle.md?plain=1#L10170-L10205