dell-laptop: rkill whitelist Precision models

Given that Precision mobile workstations are top of the line Dell products,
I expect the functionality of rfkill there to be as reliable as on Latitudes
so whitelist Precisions.

https://bugzilla.kernel.org/show_bug.cgi?id=65731



Reported-by: Calum Lind <calumlind@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>