Input: apple_z2 - fix potential confusion in Kconfig

Add a dependency on ARCH_APPLE and clarify the description to make it
more obvious that this is for ARM machines, not x86 ones.

Signed-off-by: Sasha Finkelstein <fnkl.kernel@gmail.com>
Link: https://lore.kernel.org/r/20250225-z2-kconfig-v1-1-a67d9b778a6c@gmail.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>