ice: cleanup misleading comment

The maximum Admin Queue buffer size and NVM shadow RAM sector size are both
4 Kilobytes. Some comments refer to those as 4Kb which can be confused with
4 Kilobits. Update the comments to use the commonly used KB symbol instead.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>