ice: fix overlong string, update stats output

A test started warning on a string truncation. This led to an unfortunate
realization that we are likely not accounting for the stats length
correctly before this patch, so fix the issue by putting "port." in front
of all the PF stats, instead of magically prepending it at runtime.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>