MIPS: Correct HI/LO rela reloc howto special_function entries

MIPS: Correct HI/LO rela reloc howto special_function entries

The patch corrects the mips16 and micromips rela tables to *not*
use _bfd_mips_elf_{hi,lo}16_reloc.  These special functions are
inappropriate for RELA relocs where addends are in the reloc rather
than in the section contents.  See corresponding rela R_MIPS howtos.

bfd/
	* elf64-mips.c (mips16_elf64_howto_table_rela)
	<R_MIPS16_HI16, R_MIPS16_LO16>: Use _bfd_mips_elf_generic_reloc
	special_function.
	(micromips_elf64_howto_table_rela)
	<R_MICROMIPS_HI16, R_MICROMIPS_LO16>: Similarly.
	* elfn32-mips.c: As for elf64-mips.c.