ipc4: replace fw_reg spinlock with mutex #22871

Job	Run time
build-windows (mnfst, imx8m imx8ulp)	11m 36s
LP64-WIP	4m 16s
build-linux (mnfst, ptl)	6m 12s
build-linux (mnfst, lnl)	4m 35s
build-linux (-d, mnfst, lnl)	4m 47s
build-windows (mnfst, tgl)	11m 53s
build-windows (mnfst, ptl)	10m 54s
build-linux (mnfst, mtl)	5m 1s
build-linux (mnfst, tgl-h)	4m 22s
build-linux (mnfst, imx8m imx8ulp)	5m 5s
build-windows (mnfst, mtl)	8m 50s
build-linux (mnfst, wcl imx95)	7m 31s
build-windows (-d, mnfst, lnl)	9m 18s
build-windows (mnfst, imx8 imx8x)	10m 17s
build-windows (mnfst, lnl)	10m 19s
build-windows (mnfst, tgl-h)	9m 34s
build-linux (mnfst, tgl)	4m 27s
manifest-check	2m 59s
build-linux (mnfst, imx8 imx8x)	5m 18s
compare-linux-win	30s
	2h 17m 44s

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