Fixed incorrect carrier name shown in dialog

The default data sub selection dialog was popped with
default carrier name "CARD x". The reason is that the dialog
was popped up too early before the display name was set correctly.

Fixed by correctly checking if carrier config is loaded in
MultiSimSettingController.

Test: Manually insert 2nd SIM and verify the correct name shown in dialog
Test: Basic telephony functionality tests
Test: atest MultiSimSettingControllerTest
Fix: 301987330
Change-Id: I2dfffb9ccd3a6b093dc295e2bd177ec608abba63