x86/cpuid: Remove transitional <asm/cpuid.h> header

All CPUID call sites were updated at commit:

    968e3000 ("x86/cpuid: Set <asm/cpuid/api.h> as the main CPUID header")

to include <asm/cpuid/api.h> instead of <asm/cpuid.h>.

The <asm/cpuid.h> header was still retained as a wrapper, just in case
some new code in -next started using it.  Now that everything is merged
to Linus' tree, remove the header.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250815070227.19981-2-darwi@linutronix.de