Inconsistent comment about the use of copy engine

[ye-luo]

The implementation says "main copy engine"

unified-runtime/source/adapters/level_zero/device.cpp

Line 1089 in 02ffa90

return std::pair<int, int>(0, 0); // Only main copy engine will be used.

but the above comment says "no copy engines"

  // If the environment variable is not set, no copy engines are used when
  // immediate commandlists are being used. For standard commandlists all are
  // used.

Please clarify.