Phone: Removing the unreachable call forward option

Some carriers require to remove the  unreachable
call forward option in GSM mode.

Change-Id: I18b782fe83256dcf57956b23e11cdf478a48979e
Signed-off-by: anerikg <anerikgames@gmail.com>

Conflicts:
	res/values/config.xml
Phone: The option should be clickable after pressing OK

If there's something wrong with the setting, it will return
response error and set the preference unable.

Don't set the preference unable when it returns error.

CRs-Fixed: 402479

Change-Id: I3ce8aef17ce11fbaec64d01cbbc5b00ea7efe3e7
TeleService: Prompt user the fixed dialing number can’t be empty

It does not check if the fixed dialing number is null or not,
so it also can be saved as FDN when the fixed dialing number is null.

When the number is null, we do not save it as FDN, and show a toast
to prompt user the fixed dialing number can’t be empty.

CRs-Fixed: 522515

Change-Id: I0a78be0657cdd35ed00058bb825d2e077f52b471
Signed-off-by: anerikg <anerikgames@gmail.com>

Conflicts:
	res/values-zh-rCN/cm_strings.xml
	res/values-zh-rTW/cm_strings.xml