x86: merge winchip-2 and winchip-2a cpu choices

The Winchip-2 and Winchip-2A cpu choices select the
same options for kernel and compiler.

Merge them to save few bytes and reduce confusion.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>