Fix tone region(for US, CA and JP) recognition for dual SIM

Value of "gsm.operator.iso-country" differs between the case of single
SIM device and the case of dual SIM device with only one SIM enabled.
This change makes ToneGenerator detect region in case there is only
one SIM enabled in dual SIM device.

Change-Id: I771858ec9d85054d90d7d8141266655b42b093b9
1 file changed