Previously the driver tweaked txqueuelen to avoid false Tx hang reports
seen at half duplex.  This had the effect of overriding user set values
on link change/reset. Testing shows that adjusting only the timeout
factor is sufficient to prevent Tx hang reports at half duplex.

This patch removes all instances of tx_queue_len in the driver.

Based on e1000e patch by Franco Fichtner <franco@lastsummer.de>

CC: Franco Fichtner <franco@lastsummer.de>
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>