ixgbe: add queue start failure check

For ixgbe, when queue start fails, for example, mbuf allocate
failure, the device will still start successfully, which could be
an issue.

Add return status check of queue start to avoid this issue.

Signed-off-by: Michael Qiu <michael.qiu@intel.com>
Acked-by: Thomas Monjalon <thomas.monjalon@6wind.com>