(ps-begin-job): Remove two unneeded string-as-unibyte calls

* lisp/ps-print.el (ps-begin-job): Remove two unneeded
string-as-unibyte calls to avoid byte compilation warnings.
1 job for master in 61 minutes (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #1800
test-all

01:01:00

 
Name Stage Failure
failed
test-all Test
Makefile:318: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:293: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
make: *** [check-expensive] Error 2
Makefile:957: recipe for target 'check-expensive' failed
ERROR: Job failed: exit code 1