[llvm] [Mips] Add the missing judgment when processing function handleMFLOSlot (PR #121463)

[YunQiang Su via llvm-commits]

================
@@ -0,0 +1,67 @@
+; RUN: llc -filetype=asm < %s -mcpu=mips2 | FileCheck %s -check-prefixes=MIPS2
+;
----------------
wzssyqa wrote:

We should keep the IR file simple.
we can use 
```
RUN: llc -filetype=asm --mtriple=mips -mcpu=mips2 < %s | FileCheck %s -check-prefixes=MIPS2
```

So that we won't need 
```
target datalayout = "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64"
target triple = "mips-unknown-freebsd"
```

https://github.com/llvm/llvm-project/pull/121463