Fix enabling send password by Talk with same password in mail shares

When "send password by Talk" is enabled in a mail share a new password
must be also set. However, when the passwords of the original and the
new share were compared it was not taken into account that the original
password is now hashed, while the new one is not (unless no new password
was sent, in which case the password of the original share was set in
the new share by the controller, but that was already prevented due to
both passwords being literally the same), so it was possible to set the
same password again.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>