Added indication update mode support

Adde the indication update mode support so that a system
component can control the behavior of indication update. This
will be used by the bluetooth stack when some BT devices such like
carkit is connected, modem will continue update the signal strength
even when the screen is off.

Test: Manual
Bug: 65112388
Merged-In: I4bb4894eaaba401f655e5dc25138275f5e8498e1
Change-Id: I4bb4894eaaba401f655e5dc25138275f5e8498e1
(cherry picked from commit 1a1c3575)