Fix mvno match data is incorrect for APNs

[Cause of Defect]
When user editing an existing apn, ApnPreference won't pass
the subId to ApnEditor.
As a result, if use change the mvno type to 'imsi', ApnEditor
can NOT fetch the correct IMSI due to invalid subId.

[How To Fix]
Pass subId to ApnEditor, which is same as adding new APN.

Bug: 34646368
Test: manual - edited an existing apn
Change-Id: I79fe55ccdeb8dab0ffcc7dfb22ba680beb58b9cd