tests: util: Fixup util_open() parameter order

util_open() takes a device parameter, followed by a module parameter.
The existing tests used the drmOpen() function, which uses a different
ordering of the parameters, and the old ordering was accidentally kept
during the conversion.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>