[mlir][ArmSME] Remove func patterns from vector lowering (#121640)
Remove `func.call` and `func.return` patterns from
`populateArmSVELegalizeForLLVMExportPatterns`. This function is called
from `ConvertVectorToLLVMPass::runOnOperation`. That pass should lower
only `vector` dialect ops, not `func` dialect ops. These patterns also
seem to be unnecessary, as no test cases are failing without them. Also
note that there is no `func.func` pattern, so any application of the
above-mentioned patterns produces invalid IR.