Send DTMF tones for dialing call

Fallback to active call only if outgoing call is not present.

Bug: 18224969
Change-Id: Ic3238bf539fe2188dce8ed4010652a6fc26a6435
Merge tag 'android-5.0.1_r1' of https://android.googlesource.com/platform/packages/apps/InCallUI into L

Android 5.0.1 release 1