up_down_mixer: Fix module to work as loadable module #202

Job	Run time
build-linux (mnfst, imx8 imx8x imx8m)	54s
LP64-WIP	3m 41s
build-windows (imx8 imx8x imx8m)	3m 5s
build-linux (mnfst, tgl tgl-h)	40s
build-linux (mnfst, mtl)	51s
manifest-check	43s
build-linux (mnfst, lnl)	46s
build-windows (tgl tgl-h)	3m 7s
build-linux (mnfst, -i IPC4 tgl tgl-h)	53s
build-windows (mtl)	2m 48s
build-windows (-i IPC4 tgl tgl-h)	2m 48s
build-windows (-d, mtl)	2m 17s
build-linux (zmain, imx8 imx8x imx8m)	55s
build-linux (zmain, tgl tgl-h)	1m 0s
build-linux (zmain, mtl)	44s
build-linux (zmain, lnl)	1m 0s
build-linux (zmain, -i IPC4 tgl tgl-h)	45s
build-linux (-d, mnfst, mtl)	48s
compare-linux-win	18s
	28m 3s

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