[llvm] [LLVM][AArch64] Remove aliases of LSUI instructions (PR #126072)

[Jonathan Thackray via llvm-commits]

================
@@ -0,0 +1,40 @@
+// RUN: llvm-mc -triple aarch64 -mattr=+lse -mattr=+lsui -show-encoding %s  | FileCheck %s
+// RUN: not llvm-mc -triple aarch64 -mattr=+lsui -show-encoding %s 2>&1  | FileCheck %s --check-prefix=ERROR
+
+_func:
+// CHECK: _func:
+
+//------------------------------------------------------------------------------
+// CAS(P)T instructions
----------------
jthackray wrote:

this comment needs updating
```suggestion
// CAS(P) instructions
```

https://github.com/llvm/llvm-project/pull/126072