Change in coreboot[master]: arch/x86/id.S: Fix building with clang

[Paul Menzel (Code Review)]

Attention is currently required from: Arthur Heymans, Kyösti Mälkki.
Paul Menzel has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51500 )

Change subject: arch/x86/id.S: Fix building with clang
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Patch Set 2:

(1 comment)

Commit Message:

https://review.coreboot.org/c/coreboot/+/51500/comment/6654c0b2_01809197 
PS1, Line 7: arch/x86/id.S: Fix building with clang
> Can you quote the error message this fixes?

```
    CC         bootblock/arch/x86/id.o
/tmp/id-35b17a.s:35:7: error: expected relocatable expression
.long - ver
      ^
/tmp/id-35b17a.s:36:7: error: expected relocatable expression
.long - vendor
      ^
/tmp/id-35b17a.s:37:7: error: expected relocatable expression
.long - part
      ^
```