x86: Disable CONFIG_X86_DECODER_SELFTEST in allmod/allyesconfigs

It can take some time to validate the image, make sure
{allyes|allmod}config doesn't enable it.

I'd say randconfig will cover it often enough, and the failure is also
borderline build coverage related: you cannot really make the decoder
test fail via source level changes, only with changes in the build
environment, so I agree with Andi that we can disable this one too.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Suggested-and-acked-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>