[llvm] [ARM] FIX: change `pkhtb` custom parsing produce NoMatch rather than Error (PR #85765)

[Jonathan Thackray via llvm-commits]

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@@ -235,10 +235,10 @@
 @ CHECK-ERRORS: error: immediate value out of range
 @ CHECK-ERRORS:         pkhtb r2, r2, r3, asr #33
 @ CHECK-ERRORS:                                ^
-@ CHECK-ERRORS: error: lsl operand expected.
+@ CHECK-ERRORS: error: shift operator is malformed for this instruction
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jthackray wrote:

I can see you've added a new testcase in basic-arm-instructions.s for the specific failure mentioned in the bug report, but is this change because you've added the new error message? Presumably this is now reached instead, hence the change in this testcase?

https://github.com/llvm/llvm-project/pull/85765