x86/cpuid: Include <linux/build_bug.h> in <asm/cpuid.h>

<asm/cpuid.h> uses static_assert() at multiple locations but it does not
include the CPP macro's definition at linux/build_bug.h.

Include the needed header to make <asm/cpuid.h> self-sufficient.

This gets triggered when cpuid.h is included in new C files, which is to
be done in further commits.

Fixes: 43d86e3c ("x86/cpu: Provide cpuid_read() et al.")
Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250304085152.51092-5-darwi@linutronix.de