ixgbe: Simplify transmit cleanup path

ixgbe: Simplify transmit cleanup path

This patch helps to simplify the work being done by the transmit path by
removing the unnecessary compares between count and the work limit.  Instead
we can simplify this by just adding a budget value that will act as a count
down from the work limit value.

(cherry picked from commit 30065e63d8366b6ea4c8962fa255adfac157ce06)
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Joe Jin <joe.jin@oracle.com>