Trying to create a context across multiple devices that already have peer access enabled causes an error

[ingowald]

Whenc reating a context across multple devices OWL enabels peer access between those two devices; however, CUDA actually emits an error when trying to enable peer access on a device that already has this enabled, which then causes OWL's error checking to assume that something went wrong.

Need to squash this error; all we care about is that the device will have peer access, we don't care whether it could do that before already or not.