ARM: dts: msm: Add speaker device for APQ8084 liquid

Loud Speakers on APQ8084 uses an external CLASS D amplifier,
which needs to be enabled for speaker operation. Class D AMP
is turned on by supplying voltage from regulator and by pulling
MMP6 line in PMIC high, which works as CLASS_D_EN for external
speakers PA.

Change-Id: I3589ae97c6f645af8f40debb2aa99af30cb07a0e
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>