alsa-mixer: Add support for the Center/LFE element

We already supported the CLFE element, which should be semantically
equivalent, so I just copied all the CLFE element definitions.

The Center/LFE element is seen on Creative X-Fi with 20K1 chipset cards.

Fixes: https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/issues/978

src/modules/alsa/mixer/paths/analog-output-headphones.conf

@@ -160,4 +160,8 @@ volume = off
 switch = off
 volume = off
 
+[Element Speaker Center/LFE]
+switch = off
+volume = off
+
 .include analog-output.conf.common

src/modules/alsa/mixer/paths/analog-output-lineout.conf

@@ -181,6 +181,12 @@ volume = merge
 override-map.1 = all-center
 override-map.2 = all-center,lfe
 
+[Element Center/LFE]
+switch = mute
+volume = merge
+override-map.1 = all-center
+override-map.2 = all-center,lfe
+
 [Element Bass Speaker]
 switch = off
 volume = off

src/modules/alsa/mixer/paths/analog-output-speaker-always.conf

@@ -174,4 +174,10 @@ volume = merge
 override-map.1 = all-center
 override-map.2 = all-center,lfe
 
+[Element Center/LFE]
+switch = mute
+volume = merge
+override-map.1 = all-center
+override-map.2 = all-center,lfe
+
 .include analog-output.conf.common

src/modules/alsa/mixer/paths/analog-output-speaker.conf

@@ -220,6 +220,12 @@ volume = merge
 override-map.1 = all-center
 override-map.2 = all-center,lfe
 
+[Element Center/LFE]
+switch = mute
+volume = merge
+override-map.1 = all-center
+override-map.2 = all-center,lfe
+
 [Element Speaker CLFE]
 switch = mute
 volume = merge

src/modules/alsa/mixer/paths/analog-output.conf

@@ -79,4 +79,10 @@ volume = merge
 override-map.1 = all-center
 override-map.2 = all-center,lfe
 
+[Element Center/LFE]
+switch = mute
+volume = merge
+override-map.1 = all-center
+override-map.2 = all-center,lfe
+
 .include analog-output.conf.common