x86/cacheinfo: Properly name amd_cpuid4()'s first parameter

x86/cacheinfo: Properly name amd_cpuid4()'s first parameter

amd_cpuid4()'s first parameter, "leaf", is not a CPUID leaf as the name
implies.  Rather, it's an index emulating CPUID(4)'s subleaf semantics;
i.e. an ID for the cache object currently enumerated.  Rename that
parameter to "index".

Apply minor coding style fixes to the rest of the function as well.

[ darwi: Move into a separate commit and write commit log.
	 Use "index" instead of "subleaf" for amd_cpuid4() first param,
	 as that's the name typically used at the whole of cacheinfo.c. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250324133324.23458-7-darwi@linutronix.de