Telephony: Introduce config item for Hot Swap support

When a Uicc Card is inserted or removed, Android pops up a prompt
to the user to reboot the device. This prompt is unnecessary if the
modem supports Hot Swapping of cards.

Introduce a new config item to indicate if the modem supports
hotswapping. Frameworks can then check this before propmting the
user.

Change-Id: I60c33d1f83d4f5b889b5f54bee0846675fbbb380