driver variable fix

tasks/minikube_pre_reqs.yml

@@ -53,10 +53,10 @@
 
 - name: set the macOS default driver
   set_fact:
-    driver: hyperkit
-  when: ansible_os_family == "Darwin"
+    minikube_driver: hyperkit
+  when: ansible_os_family == "Darwin" && minikube_driver_override is not defined
 
 - name: set the linux default driver
   set_fact:
-    driver: kvm2
-  when: ansible_os_family == "RedHat" or ansible_os_family == "CentOS" or ansible_os_family == "Debian"
+    minikube_driver: kvm2
+  when: (ansible_os_family == "RedHat" or ansible_os_family == "CentOS" or ansible_os_family == "Debian") && minikube_driver_override is not defined