HTCQualcommRIL: skip setCdmaSubscriptionSource if CDMA_SUBSCRIPTION_MODE is null

Change-Id: Idf842a6def9151d500bcb2d8ee3e21010c725e20
Merge "HTCQualcommRIL: skip setCdmaSubscriptionSource if CDMA_SUBSCRIPTION_MODE is null" into cm-10.2
Merge branch 'cm-10.2' into martincz