ResetPassword("") works again, thus enabling password DPM tests

With commit f8f56bce428bb2b89d1d572ccd2d604761dbbce8 the
ResetPassword("") removes the Password, instead of setting it
to an empty string.

Now we can again run the password related CTS tests

Bug: 17496766
Change-Id: I2456d40ca365bff8ef6f986193cd3ab654d6950b
1 file changed