[CIR][ThroughMLIR] Fix FuncOp for functions with pointer arguments.

[Kritoooo]

This PR is to fix the issue #658 . Now we can get the correct result using the following command.

echo "void test(int *){}" |  ./build/Debug/bin/clang -cc1 -triple x86_64-unknown-linux-gnu -fclangir -fno-clangir-direct-lowering -emit-mlir -o -

result:

module attributes {cir.lang = #cir.lang<c>, cir.sob = #cir.signed_overflow_behavior<undefined>, cir.triple = "x86_64-unknown-linux-gnu", dlti.dl_spec = #dlti.dl_spec<#dlti.dl_entry<!llvm.ptr, dense<64> : vector<4xi64>>, #dlti.dl_entry<i1, dense<8> : vector<2xi64>>, #dlti.dl_entry<f16, dense<16> : vector<2xi64>>, #dlti.dl_entry<i32, dense<32> : vector<2xi64>>, #dlti.dl_entry<i8, dense<8> : vector<2xi64>>, #dlti.dl_entry<i16, dense<16> : vector<2xi64>>, #dlti.dl_entry<!llvm.ptr<272>, dense<64> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<271>, dense<32> : vector<4xi64>>, #dlti.dl_entry<!llvm.ptr<270>, dense<32> : vector<4xi64>>, #dlti.dl_entry<f128, dense<128> : vector<2xi64>>, #dlti.dl_entry<f64, dense<64> : vector<2xi64>>, #dlti.dl_entry<f80, dense<128> : vector<2xi64>>, #dlti.dl_entry<i128, dense<128> : vector<2xi64>>, #dlti.dl_entry<i64, dense<64> : vector<2xi64>>, #dlti.dl_entry<"dlti.stack_alignment", 128 : i64>, #dlti.dl_entry<"dlti.endianness", "little">>, llvm.data_layout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"} {
  func.func @test(%arg0: memref<i32> loc(fused[#loc3, #loc4])) {
    %alloca = memref.alloca() {alignment = 8 : i64} : memref<memref<i32>> loc(#loc7)
    memref.store %arg0, %alloca[] : memref<memref<i32>> loc(#loc5)
    return loc(#loc2)
  } loc(#loc6)
} loc(#loc)

And the test/CIR/Lowering/ThroughMLIR/dot.cir now passes the test, so I have removed the XFAIL flag.