net/fs_enet: remove redundant messages for performance

Currently when we do a packet flood to the Ethernet port, the console
reports error every time when a packet is dropped.  This is too
redundant and cost performance.  Remove message for this type of event.

Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>