urls for phone setup and delete are botched

[jpaniagualaconich]

Expected Behavior

They should be:

• '/account/two_factor/phone/register/'
• '/account/two_factor/phone/unregister/42/'.

Current Behavior

They are:

• '/account/two_factor/phone/account/two_factor/backup/phone/register/'
• '/account/two_factor/phone/account/two_factor/backup/phone/unregister/42/'.

Steps to Reproduce (for bugs)

$ DJANGO_SETTINGS_MODULE=tests.settings PYTHONPATH=. django-admin shell
>>> from django.urls import reverse
>>> reverse('two_factor:phone_create')
'/account/two_factor/phone/account/two_factor/backup/phone/register/'
>>> reverse('two_factor:phone_delete', args=(42,))
'/account/two_factor/phone/account/two_factor/backup/phone/unregister/42/'