i40e: fix passing wrong error code to i40e_open()

The commit 6c167f58 ("i40e: Refactor and cleanup i40e_open(),
adding i40e_vsi_open()") introduced a new function i40e_vsi_open()
with the regression by a typo. Due to the commit, the wrong error
code would be passed to i40e_open(). Fix this error in
i40e_vsi_open() by turning the macro into a negative value so that
i40e_open() could return the pertinent error code correctly.

Fixes: 6c167f58

 ("i40e: Refactor and cleanup i40e_open(), adding i40e_vsi_open()")
Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>