tc-z8k.c: make some argument types bfd_reloc_code_real_type

gas/ChangeLog:

2016-07-19  Trevor Saunders  <tbsaunde+binutils@tbsaunde.org>

	* config/tc-z8k.c (newfix): Make type of type argument
	bfd_reloc_code_real_type.
	(apply_fix): Likewise.