ipc4: replace fw_reg spinlock with mutex #22891

Job	Run time
manifest-check	2m 40s
LP64-WIP	4m 32s
build-windows (mnfst, imx8 imx8x)	10m 3s
build-windows (mnfst, lnl)	10m 14s
build-windows (mnfst, mtl)	10m 4s
build-linux (mnfst, imx8m imx8ulp)	5m 35s
build-linux (mnfst, imx8 imx8x)	5m 29s
build-windows (mnfst, imx8m imx8ulp)	10m 39s
build-windows (-d, mnfst, lnl)	8m 54s
build-windows (mnfst, tgl)	9m 41s
build-linux (mnfst, mtl)	5m 20s
build-windows (mnfst, ptl)	11m 2s
build-linux (mnfst, ptl)	6m 30s
build-linux (mnfst, tgl)	4m 55s
build-windows (mnfst, tgl-h)	8m 41s
build-linux (mnfst, lnl)	5m 39s
build-linux (-d, mnfst, lnl)	5m 12s
build-linux (mnfst, tgl-h)	4m 21s
build-linux (mnfst, wcl imx95)	7m 3s
compare-linux-win	32s
	2h 17m 6s

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