There's already existing logic to handle this on other targets, so
this patch just makes nios2 use it.

2020-01-31  Sandra Loosemore  <sandra@codesourcery.com>

	bfd/
	* elf-eh-frame.c (_bfd_elf_write_section_eh_frame): DW_EH_PE_datarel
	encodings are relative to the GOT on nios2, too.