6.12: fix cpufreq_schedutil compatibility

Kernel 6.12.52+ changed sg_cpu->sg_policy->limits_changed assignment to use WRITE_ONCE() for proper memory ordering. Update the BMQ scheduler patch to match this change: - sg_cpu->sg_policy->limits_changed = true; + WRITE_ONCE(sg_cpu->sg_policy->limits_changed, true); Without this fix, BMQ scheduler fails to build on kernel 6.12.52+. Tested in Gentoo repo with multi-versions: https://github.com/Szowisz/CachyOS-kernels/blob/8424c1c560cf672896e51e1e90017484426ebc75/sys-kernel/cachyos-sources/cachyos-sources-6.12.63.ebuild#L124