net/mlx4: remove isolated mode constraint
net/mlx4: remove isolated mode constraint

Considering the remaining functionality, the only difference between
isolated and non-isolated mode is that a default MAC flow rule is present
with the latter.

The restriction on enabling isolated mode before creating any queues can
therefore be lifted.

Signed-off-by: Adrien Mazarguil <9d39ea493ca46c560334f650ac5d4b5ffbcb5cf0@6wind.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk