x86/cpuid: Standardize on u32 in <asm/cpuid/api.h>

Convert all uses of 'unsigned int' to 'u32' in <asm/cpuid/api.h>.

This is how a lot of the call sites are doing it, and the two
types are equivalent in the C sense - but 'u32' better expresses
that these are expressions of an immutable hardware ABI.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Xin Li (Intel) <xin@zytor.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: "Ahmed S. Darwish" <darwi@linutronix.de>
Cc: x86-cpuid@lists.linux.dev
Link: https://lore.kernel.org/r/20250317221824.3738853-5-mingo@kernel.org