i40e: initialize params before notifying of l2_param_changes

Probably due to some mis-merging fix a bug associated with commits
d7ce6422

 ("i40e: don't check params until after checking for client
instance", 2017-02-09) and 3140aa9a78c9 ("i40e: KISS the client
interface", 2017-03-14)

The first commit tried to move the initialization of the params
structure so that we didn't bother doing this if we didn't have a client
interface. You can already see that it looks fishy because of the
indentation. The second commit refactors a bunch of the interface, and
incorrectly drops the params initialization.

I believe what occurred is that internally the two patches were
re-ordered, and the merge conflicts as a result were performed
incorrectly.

Fix the use of an uninitialized variable by correctly initializing the
params variable via i40e_client_get_params().

Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>