Fix enabling of submit button

Change I478c915b introduced a regression where the submit
button is enabled even if no password is entered for a secure
network.

This happened because our checks would override a password
check when IP and proxy settings are valid (which is the default
setting)

Bug: 4462439
Change-Id: Icd3fde90759f33fa391ec79ae8075b6d8388d2e9