i40e: change behavior on PF in response to MDD event

TX MDD events reported on the PF are the result of the
PF misconfiguring a descriptor and not because of "bad actions"
by anything else.  No need to reset now because if it
results in a Tx hang, the Tx hang check will take care of it.

Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>