x86/kconfig: Select ARCH_WANT_FRAME_POINTERS again when UNWINDER_FRAME_POINTER=y

It took me some time to understand the purpose of the tricky code at
the end of arch/x86/Kconfig.debug.

Without it, the following would be shown:

  WARNING: unmet direct dependencies detected for FRAME_POINTER

because

  81d38719 ("x86/kconfig: Consolidate unwinders into multiple choice selection")

removed 'select ARCH_WANT_FRAME_POINTERS'.

The correct and more straightforward approach should have been to move
it where 'select FRAME_POINTER' is located.

Several architectures properly handle the conditional selection of
ARCH_WANT_FRAME_POINTERS. For example, 'config UNWINDER_FRAME_POINTER'
in arch/arm/Kconfig.debug.

Fixes: 81d38719

 ("x86/kconfig: Consolidate unwinders into multiple choice selection")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240204122003.53795-1-masahiroy@kernel.org