ARM: dts: msm: Add ep92 audio_mute pin

The external EP92 chip provides a dedicated line to signal mute
condition. Add IRQ and GPIO information for the same.
Also add the IRQ to wakeup HLOS on EP92 events.

Change-Id: Iaa6d5b0fac7f872e5a2c0b4908fe9b91d8918911
Signed-off-by: Ralf Herz <rherz@codeaurora.org>