Use SubscriptionManager.ACTION_DEFAULT_SUBSCRIPTION_CHANGED instead

Change deprecated TelephonyIntents.ACTION_DEFAULT_SUBSCRIPTION_CHANGED
as SubscriptionManager.ACTION_DEFAULT_SUBSCRIPTION_CHANGED.
And clean up the code to
 - use int type for subscription Id
 - get new default PhoneId corresponding to new default SubId for no
 value

Test: Manual

Change-Id: I3084ca5d477c7f3861061ee2b17906fd2e7e5d46
Signed-off-by: Taesu Lee <taesu82.lee@samsung.com>