i40e: avoid use of uninitialized v_budget in i40e_init_msix

This I40E_FCOE block increments v_budget before it has been initialized,
then v_budget gets overwritten a few lines later.  This patch just
reorders the code hunks in what I believe was the intended sequence.

Coverity: CID 12600999

Signed-off-by: John W Linville <linville@tuxdriver.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>