Mips: Improve MipsAsmParser::expandDivRem (#172967)
Fixes: #172965
In fact MipsAsmParser::expandDivRem is in a so bad status:
1. Div may not execute at all in most case
```
.set reorder
bnez $3, $tmp0
div $zero, $2, $3
break 7
$tmp0:
```
`.set reorder` may insert a nop after bnez, which will skip `div` if $3
is not zero.
2. `break 6` is wrong here.
