drivers: net: xgene: Fix the order of the arguments of 'alloc_etherdev_mqs()'

'alloc_etherdev_mqs()' expects first 'tx', then 'rx'. The semantic here
looks reversed.

Reorder the arguments passed to 'alloc_etherdev_mqs()' in order to keep
the correct semantic.

In fact, this is a no-op because both XGENE_NUM_[RT]X_RING are 8.

Fixes: 107dec27

 ("drivers: net: xgene: Add support for multiple queues")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>