i40e: Don't stop driver probe when querying DCB config fails

i40e: Don't stop driver probe when querying DCB config fails

Commit id: 014269ff376f552363ecdab78d3d947fbe2237d9 in Linus's tree
should be queued up for stable 3.14 & 3.15 since the i40e driver will
not load when DCB is enabled, unless this patch is applied.

In case of any AQ command to query port's DCB configuration fails
during driver's probe time; the probe fails and returns an error.

This patch prevents this issue by continuing the driver probe even
when an error is returned.

Also, added an error message to dump the AQ error status to show what
error caused the failure to get the DCB configuration from firmware.

Change-ID: Ifd5663512588bca684069bb7d4fb586dd72221af
Signed-off-by: Neerav Parikh <neerav.parikh@intel.com>
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>