9bc3f24a98
Add missing alloc_cpu_id() function (atomic round-robin CPU selection). Fix type chain: MsiAllocation.irq u8→u32 to match allocate_irq_vector return type. irq_set_affinity accepts u32 irq for consistency. Verified: driver-sys compiles on Linux (x86_64-unknown-linux-gnu). Full redbear-mini image builds and boots in QEMU.