[SYCL][NFC] Remove an outdated comment from queue impl (#19079)

I think the member is self explanatory, hence no replacement comment.

Author: aarongreig

sycl/source/detail/queue_impl.hpp

@@ -1000,7 +1000,6 @@ class queue_impl : public std::enable_shared_from_this<queue_impl> {
   const async_handler MAsyncHandler;
   const property_list MPropList;
 
-  /// List of queues created for FPGA device from a single SYCL queue.
   ur_queue_handle_t MQueue;
 
   // Access should be guarded with MMutex