i40e: Fix configure TCs after initial DCB disable

in commit a036244c068612a43fa8c0f33a0eb4daa4d8dba0 a fix
was put into place to avoid a kernel panic when a non-
supported traffic class configuration was put into place
and then lldp was enabled/disabled on the link partner
switch.  This fix caused it to be necessary to
unload/reload the driver to reenable DCB once a supported
TC config was in place.

The root cause of the original panic was that the function
i40e_pf_get_default_tc was allowing for a default TC other
than TC 0, and only TC 0 is supported as a default.

This patch removes the get_default_tc function and replaces
it with a #define since there is only one TC supported as
a default.

Change-Id: I448371974e946386d0a7718d73668b450b7c72ef
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Tested-by: Ronald Bynoe <ronald.j.bynoe@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e.h b/drivers/net/ethernet/intel/i40e/i40e.h
index 2030d7c..6d61e44 100644
--- a/drivers/net/ethernet/intel/i40e/i40e.h
+++ b/drivers/net/ethernet/intel/i40e/i40e.h
@@ -92,6 +92,7 @@
 #define I40E_AQ_LEN			256
 #define I40E_AQ_WORK_LIMIT		66 /* max number of VFs + a little */
 #define I40E_MAX_USER_PRIORITY		8
+#define I40E_DEFAULT_TRAFFIC_CLASS	BIT(0)
 #define I40E_DEFAULT_MSG_ENABLE		4
 #define I40E_QUEUE_WAIT_RETRY_LIMIT	10
 #define I40E_INT_NAME_STR_LEN		(IFNAMSIZ + 16)