ucm2: Librem_5: create a first working profile for the external mic

the settings are all based on a discussion with Charles:
https://lore.kernel.org/alsa-devel/20220207142129.GB112838@ediswmail.ad.cirrus.com/

Currently we don't get any signal from the external mic. These settings
result in at least a usable signal (we can try to further improve later).

There are 3 Volume controls for the analog parts, all before the ADC.
In order from Jack to ADC, they are:

numid=10,iface=MIXER,name='Capture Volume'
   ; type=INTEGER,access=rw---R--,values=2,min=0,max=63,step=0
   : values=63,63
   | dBscale-min=-23.25dB,step=0.75dB,mute=0

"Input PGA Volume Control". 31=0dB. We use 39=+6dB.

numid=7,iface=MIXER,name='MIXINR PGA Volume'
   ; type=INTEGER,access=rw---R--,values=1,min=0,max=7,step=0
   : values=7
   | dBrange-
     rangemin=0,,rangemax=1
       | dBscale-min=0.00dB,step=6.00dB,mute=0
     rangemin=2,,rangemax=2
       | dBscale-min=13.00dB,step=13.00dB,mute=0
     rangemin=3,,rangemax=4
       | dBscale-min=18.00dB,step=2.00dB,mute=0
     rangemin=5,,rangemax=5
       | dBscale-min=24.00dB,step=0.00dB,mute=0
     rangemin=6,,rangemax=7
       | dBscale-min=27.00dB,step=3.00dB,mute=0

"Right input PGA to Right input Boost-Mixer Gain"
0=0dB. we use 1=+3dB.

numid=8,iface=MIXER,name='MIXINR IN3R Volume'
  ; type=INTEGER,access=rw---R--,values=1,min=0,max=7,step=0
  : values=6
  | dBscale-min=-15.00dB,step=3.00dB,mute=0

we don't use that since we can either route from PGA or IN3R to MIXINR.

("quotes" are from the datasheet)

default/audio/ucm2/simple-card/HiFi.conf

@@ -156,22 +156,24 @@ SectionDevice."Headset" {
 	]
 
 	EnableSequence [
-		cset "name='MIXINR IN3R Switch' on"
-		cset "name='MIXINR IN3R Volume' 7"
+		cset "name='Digital Capture Volume' 116,116"
 		cset "name='Input Mode' Analog"
+		cset "name='MIXINR PGA Volume' 1,1"
+		cset "name='MIXINR PGA Switch' on,on"
+		cset "name='Capture Volume' 39,39"
+		cset "name='Capture Switch' on,on"
 	]
 
 	DisableSequence [
-		cset "name='MIXINR IN3R Switch' off"
-		cset "name='MIXINR IN3R Volume' 0"
+		cset "name='Capture Switch' off,off"
+		cset "name='MIXINR PGA Switch' off,off"
 		cset "name='Input Mode' Digital"
 	]
 
 	Value {
 		CapturePriority "100"
 		CaptureChannels "2"
-		CaptureVolume "name='MIXINR IN3R Volume'"
-		CaptureSwitch "name='MIXINR IN3R Switch'"
+		CaptureVolume "name='Capture Volume'"
 		CapturePCM "hw:${CardId},0"
 		JackControl "Headphones Jack"
 	}