ice: add helpers for virtchnl

The virtchannel interface was repeating a lot of strings
and wasting storage space in the kernel.  There was also
inconsistent messages for the same thing.  Consolidate all
those messages and bit checks into a couple of helper functions.

Also, reduce stack space usage by simplifying getting the pointer
to the pf using a helper.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Co-developed-by: Brett Creeley <brett.creeley@intel.com>
Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>