Telephony: Avoid list of Apns in ApnSettingsMenu

Don't display any Apns in the ApnSettingsMenu when
getOperatorNumericSelection returns empty

Change-Id: I8f425e75c995f9825905983dc1bdc94f15f2054e
CRs-fixed: 486026
(cherry picked from commit 09e0403e2199c65e567775994ffe990281fc5183)
(cherry picked from commit d483b697e2acc4eef23a8cd743be97b2febdb565)
(cherry picked from commit c89dc4e90cff4d0f3342cf3862d159ff785b2a2e)