iwlagn: fix the check of IWLAGN_FIRST_AMPDU_QUEUE

BUILD_BUG_ON(ARRAY_SIZE(iwlagn_ipan_queue_to_tx_fifo) !=
						IWLAGN_FIRST_AMPDU_QUEUE);

This check can be buggy. IWLAGN_FIRST_AMPDU_QUEUE has to be greater than the
ARRAY_SIZE of iwlagn_ipan_queue_to_tx_fifo.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>