ionic: lif debugfs refresh on reset

Remove and restore the lif's debugfs pointers on a reset,
and make sure to check for the dentry before removing it
in case an earlier reset failed to rebuild the lif.

Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>