callforwarding: Fix duplicated error popup

When call forward setting fails and qeurying also responds invalid
then a duplicate popup is shown to the user.
This CL removes resetting preference before calling onError
which already reset preference.

Bug: 146532585

Change-Id: Ida6baff95d5eae52501dc07f1cb891e9238f2e17
Signed-off-by: Jang Hayeong <hayeong.jang@samsung.com>
2 files changed