ixgbe: Focus config of head, tail ntc, and ntu all into a single function

This patch makes it so that head, tail, next to clean, and next to use are
all reset in a single function for the Tx or Rx path. Previously the code
for this was spread out over several areas which could make it difficult to
track what the values for these were.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>