ipmiutil: uncomment PARALLEL_MAKE

* it's randomly failing for last year, so it wasn't there by accident
  at least one race condition is on ipmilan.o:
  | obj/ipmilan.o: file not recognized: File truncated
  | collect2: error: ld returned 1 exit status
  | make[2]: *** [libipmiutil.so] Error 1
  | make[2]: *** Waiting for unfinished jobs....
* oldest failure report was on 2015-08-30
  http://www.openembedded.org/wiki/Bitbake_World_Status_Jethro
  and many more were reported since then in:
  http://www.openembedded.org/wiki/Bitbake_World_Status_Krogoth
  http://www.openembedded.org/wiki/Bitbake_World_Status
  and even more
  http://errors.yoctoproject.org/Errors/Search/?query=ipmiutil
  e.g. good examples (not with musl)
  http://errors.yoctoproject.org/Errors/Details/88674/
  http://errors.yoctoproject.org/Errors/Details/85986/



Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>