x86/cpu: Remove CONFIG_MWINCHIP3D/MWINCHIPC6

x86/cpu: Remove CONFIG_MWINCHIP3D/MWINCHIPC6

These CPUs lack CMPXCHG8B support, according to Arnd Bergmann:

  | "Winchip6 (486-class, no tsc, no cx8) and Winchip3D
  | (486-class, with tsc but no cx8)"

Any still available derivatives, if they have TSC and CX8 support,
would work with regular Pentium builds, there's no need to have
a separate build option for them.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250425084216.3913608-3-mingo@kernel.org