m68k: Update elf_machine_load_address for static PIE

When --enable-static-pie is used to configure glibc, we need to use
_dl_relocate_static_pie to compute load address in static PIE.

	* sysdeps/m68k/dl-machine.h (elf_machine_load_address): Use
	_dl_relocate_static_pie instead of _dl_start to compute load
	address in static PIE.