Allow a device to include its own RIL subclass

For cases where a single device needs a subclass, there's no need to
pollute the common core with it: just stick it in the device's own
repository, and add something like
"BOARD_RIL_CLASS := ../../../device/manuf/model/ril/" to the BoardConfig

Conflicts:
	Android.mk

Change-Id: I9d01ceb6e5587382eb216341e2e373ec0c52848f
Initialize RIL with the correct CDMA subscription mode setting

Users choice of CDMA Subscription Source is stored in CDMA_SUBSCRIPTION_MODE
setting in database.
If telephony restarts after a crash, PhoneFactory sets the
CDMA subscription source value from PREFERRED_CDMA_SUBSCRIPTION
setting and that causes the mismatch with the value in the settings
database chosen by the user. The change is to use the
CDMA_SUBSCRIPTION_MODE setting instead when creating the RIL object.

Also, remove the Setting PREFERRED_CDMA_SUBSCRIPTION from the database.
With this change the special treatment for LTE on CDMA will not be needed.
The correct value can be set in the database for CDMA_SUBSCRIPTION_MODE
and that will be taken on power-up by this code.

Conflicts:
	src/java/com/android/internal/telephony/PhoneFactory.java

Change-Id: I11fff596a5fe721c64f192c889672326517dc43d