bfin: disable newer binutils for internal toolchain

You get following linking error, when trying to build a
toolchain for bfin with newer binutils:
bfin-buildroot-linux-uclibc/bin/ld: fde encoding in _divdi3_s.o(.eh_frame) prevents .eh_frame_hdr table being created.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>