[NFC] Fix evaluation order dependency in call arguments (#141366)
The code in `ARMAsmParser::parseDirectiveReq` passes both
`parseRegister(Reg, SRegLoc, ERegLoc)` and `SRegLoc` as arguments to
`check()`. Since function arguments are indeterminately sequenced per
C++17 [expr.call]/5, a compiler can evaluate `SRegLoc` before
`parseRegister()` executes. This means `check()` receives a null
location instead of the actual parsed source location for error
reporting.
The fix separates the calls to establish explicit sequencing, ensuring
`check()` receives the correct source location.
This issue was detected by [the CFamily analyzer for
SonarQube](https://www.sonarsource.com/knowledge/languages/cpp/). I'm
happy to provide any additional information or clarification as needed.