mips: Don't check _DYNAMIC in elf_machine_load_address

Since mips can't convert access _DYNAMIC via GOT, which needs dynamic
relocation, to PC-relative at link-time, don't check _DYNAMIC in
elf_machine_load_address.

        * sysdeps/mips/dl-machine.h (elf_machine_load_address): Don't
        check _DYNAMIC.