Fix checkout button analytics attribute.

ecommerce/templates/oscar/basket/partials/client_side_checkout_basket.html

@@ -198,7 +198,7 @@
                             data-track-category="checkout"
                             data-processor-name="{{ client_side_payment_processor_name }}"
                             data-course-id="{{ course_key }}"
-                            data-checkout-type="client_side">
+                            data-track-checkout-type="client_side">
                       {% trans "Place Order" %}
                     </button>
                 {% endif %}

ecommerce/templates/oscar/basket/partials/hosted_checkout_basket.html

@@ -154,7 +154,7 @@
                                 data-track-category="checkout"
                                 data-processor-name="{{ processor.NAME|lower }}"
                                 data-course-id="{{ course_key }}"
-                                data-checkout-type="hosted"
+                                data-track-checkout-type="hosted"
                                 class="btn payment-button"
                                 id="{{ processor.NAME|lower }}">
                             {% if processor.NAME == 'cybersource' %}