cleanup: remove deprecated vm-driver option

$ minikube start --help
...
    --vm-driver='': DEPRECATED, use `driver` instead.
...

'vm-driver' option is deprecated at minikube v1.8.0, we should really
start using 'driver'

Related: kubernetes/minikube#6888

Signed-off-by: Prasanna Kumar Kalever <prasanna.kalever@redhat.com>

scripts/minikube.sh

@@ -171,16 +171,16 @@ up)
     if minikube_supports_psp; then
         enable_psp
         # shellcheck disable=SC2086
-        ${minikube} start --force --memory="${MEMORY}" --cpus="${CPUS}" -b kubeadm --kubernetes-version="${KUBE_VERSION}" --vm-driver="${VM_DRIVER}" --feature-gates="${K8S_FEATURE_GATES}" ${EXTRA_CONFIG}
+        ${minikube} start --force --memory="${MEMORY}" --cpus="${CPUS}" -b kubeadm --kubernetes-version="${KUBE_VERSION}" --driver="${VM_DRIVER}" --feature-gates="${K8S_FEATURE_GATES}" ${EXTRA_CONFIG}
     else
         # This is a workaround to fix psp issues in minikube >1.6.2 and <1.11.0
         # shellcheck disable=SC2086
-        ${minikube} start --force --memory="${MEMORY}" --cpus="${CPUS}" -b kubeadm --kubernetes-version="${KUBE_VERSION}" --vm-driver="${VM_DRIVER}" --feature-gates="${K8S_FEATURE_GATES}"
+        ${minikube} start --force --memory="${MEMORY}" --cpus="${CPUS}" -b kubeadm --kubernetes-version="${KUBE_VERSION}" --driver="${VM_DRIVER}" --feature-gates="${K8S_FEATURE_GATES}"
         DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"
         ${minikube} kubectl -- apply -f "$DIR"/psp.yaml
         ${minikube} stop
         # shellcheck disable=SC2086
-        ${minikube} start --force --memory="${MEMORY}" --cpus="${CPUS}" -b kubeadm --kubernetes-version="${KUBE_VERSION}" --vm-driver="${VM_DRIVER}" --feature-gates="${K8S_FEATURE_GATES}" ${EXTRA_CONFIG}
+        ${minikube} start --force --memory="${MEMORY}" --cpus="${CPUS}" -b kubeadm --kubernetes-version="${KUBE_VERSION}" --driver="${VM_DRIVER}" --feature-gates="${K8S_FEATURE_GATES}" ${EXTRA_CONFIG}
     fi
 
     # create a link so the default dataDirHostPath will work for this