x86/Kconfig: Fix lists in X86_EXTENDED_PLATFORM help text

Support for STA2X11-based systems was removed in February in:

  dcbb01fb ("x86/pci: Remove old STA2x11 support")

Intel MID for 32-bit platforms was removed from this list also in
February in:

  ca5955dd ("x86/cpu: Document CONFIG_X86_INTEL_MID as 64-bit-only")

Intel MID for 64-bit platforms is a duplicate for "Merrifield/Moorefield
MID devices".

Fixes: 4047e877 ("x86/Kconfig: Update lists in X86_EXTENDED_PLATFORM")
Signed-off-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Shevchenko <andy@kernel.org>
Link: https://lore.kernel.org/r/20250322175052.43611-1-mat.jonczyk@o2.pl