i40e: Add description to misc and fd interrupts

This patch adds additional text description for base pf0 and flow director
generated interrupts.  Without this patch, these interrupts are difficult
to distinguish per port on a multi-function device.

Change-ID: I4662e1b38840757765a3fe63d90219d28e76bfab
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>