ltp: use bfd even when gold is used with ld-is-gold

ltp: use bfd even when gold is used with ld-is-gold

* version 20220527 added KVM test infrastructure which currently fails to build with gold due to
  SORT_NONE in linker script which isn't supported by gold:
  https://sourceware.org/bugzilla/show_bug.cgi?id=18097
  https://github.com/linux-test-project/ltp/commit/3fce2064b54843218d085aae326c8f7ecf3a8c41#diff-39268f0855c634ca48c8993fcd2c95b12a65b79e8d9fa5ccd6b0f5a8785c0dd6R36

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>