staging: fsl-dpaa2/eth: Add counter for skb reallocs

Add a counter for the number of egress frames that need to be
realloc'ed due to insufficient headroom space.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>