tools/x86/kcpuid: Use C99-style for loops

tools/x86/kcpuid: Use C99-style for loops

Since commit e8c07082a810 ("Kbuild: move to -std=gnu11") and the kernel
allows C99-style variable declarations inside of a for() loop.

Adjust the kcpuid code accordingly.

Note, this helps readability as some of the kcpuid functions have a huge
list of variable declarations on top.

Note, remove the empty lines before cpuid() invocations as it is clearer
to have their parameter initialization and the actual call in one block.

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>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20250324142042.29010-10-darwi@linutronix.de