I have heard some people saying that Unit testing is done primarily by the developers and test engineers need not know about Unit testing. But this is not the case, Unit testing is as important for test engineers as it is for developers.

Probably developers will write the unit test cases but your understanding of the framework and unit testing can certainly help him/her in designing the flow for unit test cases, generating test data and making good reports. All these activities will ultimately help you in the long run as product quality will increase significantly because of the efforts you put in on the unit testing.