codecs/rt5640: Specify Playback/CaptureMasterElem for HW volume-control

codecs/rt5640: Specify Playback/CaptureMasterElem for HW volume-control

Newer kernels add "aif:1" or "aif:2" to the components string to let
us know which AIF is being used.

Use this to specify the correct Playback/CaptureMasterElem for HW
volume-control, based on which AIF is being used.

On older kernels, where there is no "aif:%d" string in the components
string, no Playback/CaptureMasterElem is specified.

In DigitalMics.conf the master mixer is used as regular CaptureMixerElem
instead of as CaptureMasterElem since the DMICs don't have any analog
volume control.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>