ice: add ice_adapter for shared data across PFs on the same NIC

There is a need for synchronization between ice PFs on the same physical
adapter.

Add a "struct ice_adapter" for holding data shared between PFs of the
same multifunction PCI device. The struct is refcounted - each ice_pf
holds a reference to it.

Its first use will be for PTP. I expect it will be useful also to
improve the ugliness that is ice_prot_id_tbl.

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>