[coreboot] timestamping broke 486 board

[Rudolf Marek]

Hi

Recent addition of timestamping stuff broke the only 486 board supported by 
coreboot, the bifferboard.

It ends like this:

Jumping to image.
Unexpected Exception: 6 @ 10:001007e3 - Halting
Code: 0 eflags: 00000016
eax: 001001fe ebx: 00100118 ecx: 00000000 edx: 00108e00
edi: 0010aaf8 esi: 00000000 ebp: 00117ff4 esp: 00117fd8

Please keep in mind 486, dont use rdtsc/cpuid in generic code, or if you do make 
sure make it non-default option.

I fixed that with simple #if stuff

http://review.coreboot.org/#/c/925/

Please have a look to patch as soon as possible I wanted to announce the 
bifferboard stuff and this is kind of show stopper.

Thanks
Rudolf