hal: update combo device handling

If the wired headset/headphone/line devices are handled by
a different backend than speaker/earpiece devices, the combo
devices such as speaker+headphones can be split into individual
devices and enabled/disabled independently.

Conflicts:
	hal/msm8916/platform.c
	hal/msm8974/platform.c

Change-Id: I30e90f398ef204d106b5d8dac8fba166583bdbc8