boards: ace40: disable IMR context save #21248

Job	Run time
LP64-WIP	4m 1s
manifest-check	49s
build-windows (tgl tgl-h)	7m 18s
build-windows (-d, lnl)	6m 26s
build-windows (imx8 imx8x imx8m imx8ulp)	9m 58s
build-windows (mtl lnl)	8m 28s
build-linux (zmain, mtl lnl)	5m 43s
build-linux (mnfst, imx8 imx8x imx8m imx8ulp)	6m 29s
build-linux (mnfst, tgl tgl-h)	5m 52s
build-windows (ptl)	7m 13s
build-linux (zmain, tgl tgl-h)	5m 39s
build-linux (mnfst, ptl)	4m 20s
build-linux (zmain, imx8 imx8x imx8m imx8ulp)	7m 0s
build-linux (zmain, ptl)	4m 37s
build-linux (mnfst, mtl lnl)	5m 34s
build-linux (-d, mnfst, lnl)	4m 35s
build-linux (mnfst, --all)	16m 57s
compare-linux-win	33s
	1h 51m 32s

Provide feedback