x86/cpuid: Rename cpuid_get_leaf_0x2_regs() to cpuid_leaf_0x2()

Rename the CPUID(0x2) register accessor function:

    cpuid_get_leaf_0x2_regs(regs)

to:

    cpuid_leaf_0x2(regs)

for consistency with other <cpuid/api.h> accessors that return full CPUID
registers outputs like:

    cpuid_leaf(regs)
    cpuid_subleaf(regs)

In the same vein, rename the CPUID(0x2) iteration macro:

    for_each_leaf_0x2_entry()

to:

    for_each_cpuid_0x2_desc()

to include "cpuid" in the macro name, and since what is iterated upon is
CPUID(0x2) cache and TLB "descriptos", not "entries".  Prefix an
underscore to that iterator macro parameters, so that the newly renamed
'desc' parameter do not get mixed with "union leaf_0x2_regs :: desc[]" in
the macro's implementation.

Adjust all the affected call-sites accordingly.

While at it, use "CPUID(0x2)" instead of "CPUID leaf 0x2" as this is the
recommended style.

No change in functionality intended.

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: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: x86-cpuid@lists.linux.dev
Link: https://lore.kernel.org/r/20250508150240.172915-6-darwi@linutronix.de