ixgbe(4): Fix enabling/disabling and reconfiguration of queues

ixgbe(4): Fix enabling/disabling and reconfiguration of queues

- Wrong order of casting and bit shift caused that enabling and disabling
  queues didn't work properly for queues number larger than 32. Use literals
  with right suffix instead.

- TX ring tail address was not updated during reinitiailzation of TX
  structures. It could block sending traffic.

- Also remove unused variables 'eims' and 'active_queues'.

Submitted by:	Krzysztof Galazka <krzysztof.galazka@intel.com>
Reviewed by:	erj@
Sponsored by:	Intel Corporation
Differential Revision:	https://reviews.freebsd.org/D20826

(cherry picked from commit 2dc2d580354e95491a033fa9e21c8ef0cbd9bc42)