[z8k] committed, fix 7bit displacements.

[Christian Groessler]

I've committed the following change:

2021-03-18  Christian Groessler  <chris@groessler.org>

         * config/tc-z8k.c (apply_fix): Handle 7-bit relocations correctly.
         Problem found by Tadashi G. Takaoka <tadashi.g.takaoka@gmail.com>.

best regards,
chris