i40e: refactor interrupt enable

i40e: refactor interrupt enable

Orabug: 22342532

The interrupt enable function was always making the caller add
the base_vector from the VSI struct which is already passed to
the function. Just collapse the math into the helper function.

Change-ID: I54ef33aa7ceebc3231c3cc48f7b39fd0c3ff5806
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from commit 7845548de7e4b49451f0eed77f690e579c428417)
Signed-off-by: Brian Maly <brian.maly@oracle.com>