ixgbe: Fix return of invalid txq

a developer had complained of getting lots of warnings:

"eth16 selects TX queue 98, but real number of TX queues is 64"

http://www.mail-archive.com/e1000-devel@lists.sourceforge.net/msg02200.html

As there was no follow up on that bug, I am submitting this
patch assuming that the other return points will not return
invalid txq's, and also that this fixes the bug (not tested).

Signed-off-by: Krishna Kumar <krkumar2@in.ibm.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>