IB/hfi1: Remove snoop/diag interface

The snoop/diag interface is better served by an implementation which is
more general and usable by other drivers perhaps. Go ahead and remove
the code now and get rid of the char dev. We can put the feature back
when we have a more agreeable solution.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>