Correct a low-probability memory leak

:Release Notes:
Resolves a Coverity-detect low=probability memory leak.

:Detailed Notes:
In the case that frame buffer zero can not be opened, the error
exit fails to release the pre-allocated device data structure.

Add a free() statement to avoid the leak.

:Testing Performed:
Verification by inspection

:QA Notes:

:Issues Addressed:
[ANG-460] nyx-modules: Coverity Issues

Open-webOS-DCO-1.0-Signed-off-by: Keith Derrick <keith.derrick@lge.com>

Change-Id: Idc2a88cabf9dace79e31479476d677fc283c9777
Reviewed-on: https://g2g.palm.com/4707
Reviewed-by: DCO Verification
Reviewed-by: Keith Derrick <keith.derrick@lge.com>
Tested-by: Keith Derrick <keith.derrick@lge.com>
Reviewed-by: Anatolii Sakhnik <anatolii.sakhnik@lge.com>