[mlir][ArmSME] Suppress potential unused warning (#99573)

When building in release mode, the assert will be dropped, making
`remove` unused.

Author: wecing

mlir/lib/Dialect/ArmSME/Transforms/TileAllocation.cpp

@@ -619,6 +619,7 @@ void allocateTilesToLiveRanges(
         // Remove the live range from the active/inactive sets.
         if (!activeRanges.remove(rangeToSpill)) {
           bool removed = inactiveRanges.remove(rangeToSpill);
+          (void)removed;
           assert(removed && "expected a range to be removed!");
           (void)removed;
         }