bnxt_en: Call bnxt_dcb_init() after getting firmware DCBX configuration.

In the current code, bnxt_dcb_init() is called too early before we
determine if the firmware DCBX agent is running or not.  As a result,
we are not setting the DCB_CAP_DCBX_HOST and DCB_CAP_DCBX_LLD_MANAGED
flags properly to report to DCBNL.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>