Remove incorrect assertion for GPU timing in SYCL

Remove incorrect assertion for GPU timing in SYCL

- The expression was backwards: it was failing when timing was disabled
  instead of failing when it is enabled.
- The expression was run on a freshly-initialized data structure, and
  the value of bDoTime was always overridden later, so it was not
  actually checking anything.

Since we anyway never set bDoTime to true in SYCL build, we might as
well remove this assertion here altogether.

Introduced in !1296 (c4a672b93b655ff674b671fd10ebe728b2d19ec8).