i40e: Refactor and cleanup i40e_open(), adding i40e_vsi_open()

i40e: Refactor and cleanup i40e_open(), adding i40e_vsi_open()

This patch cleans up and moves a portion of i40e_open to i40e_vsi_open,
in order to have a shorter vsi_open function that does only that.

Change-ID: I1c418dda94dcfc0eb7d4386a70c330692ef5ecc9
Signed-off-by: Elizabeth Kappler <[email protected]>
Signed-off-by: Akeem G Abodunrin <[email protected]>
Signed-off-by: Catherine Sullivan <[email protected]>
Tested-by: Kavindya Deegala <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>