mux: remove DEMUX entry from LLEXT build

mux.toml doesn't have a demux entry in it, therefore we cannot have
one in .module either, remove it until fixed. Also fix a copy-paste
error in the same code block.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

Author: lyakh

src/audio/mux/mux.c

@@ -475,7 +475,7 @@ static const struct module_interface demux_interface = {
 DECLARE_MODULE_ADAPTER(demux_interface, demux_uuid, demux_tr);
 SOF_MODULE_INIT(demux, sys_comp_module_demux_interface_init);
 
-#if CONFIG_COMP_VOLUME_MODULE
+#if CONFIG_COMP_MUX_MODULE
 /* modular: llext dynamic link */
 
 #include <module/module/api_ver.h>
@@ -492,7 +492,12 @@ SOF_LLEXT_MOD_ENTRY(demux, &demux_interface);
 
 static const struct sof_man_module_manifest mod_manifest[] __section(".module") __used = {
 	SOF_LLEXT_MODULE_MANIFEST("MUX", mux_llext_entry, 1, UUID_MUX, 15),
-	SOF_LLEXT_MODULE_MANIFEST("DEMUX", demux_llext_entry, 1, UUID_DEMUX, 15),
+	/*
+	 * The demux entry is removed because mtl.toml doesn't have an entry
+	 * for it. Once that is fixed, the manifest line below can be
+	 * re-activated:
+	 * SOF_LLEXT_MODULE_MANIFEST("DEMUX", demux_llext_entry, 1, UUID_DEMUX, 15),
+	 */
 };
 
 SOF_LLEXT_BUILDINFO;