west.yml: Update zephyr for sof/imx-stable-v2.15.6 #23110

Job	Run time
manifest-check	2m 53s
build-windows (mnfst, tgl)	8m 43s
build-windows (mnfst, imx8m imx8ulp)	10m 34s
build-windows (-d, mnfst, lnl)	9m 32s
build-linux (mnfst, ptl)	5m 48s
build-linux (-d, mnfst, lnl)	4m 27s
build-windows (mnfst, mtl)	9m 28s
build-windows (mnfst, imx8 imx8x)	10m 25s
build-linux (mnfst, wcl imx95)	7m 56s
build-linux (mnfst, imx8m imx8ulp)	4m 58s
build-windows (mnfst, tgl-h)	10m 55s
build-windows (mnfst, lnl)	9m 36s
LP64-WIP	4m 6s
build-linux (mnfst, mtl)	5m 11s
build-linux (mnfst, tgl-h)	4m 14s
build-linux (mnfst, imx8 imx8x)	4m 39s
build-windows (mnfst, ptl)	10m 16s
build-linux (mnfst, tgl)	4m 12s
build-linux (mnfst, lnl)	4m 44s
compare-linux-win	33s
	2h 13m 10s

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