IB/hfi1: Remove ASIC block clear

The ASIC block is shared between two HFIs. Individual devices
should not initialize registers there. Retain the power-on values.
Individual users set registers as needed with one exception.
Clear sbus fast mode on "slow" calls.

Reviewed-by: Mitko Haralanov <mitko.haralanov@intel.com>
Reviewed-by: Easwar Hariharan <easwar.hariharan@intel.com>
Signed-off-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Jubin John <jubin.john@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>