When we switch to including all linker lists in SPL it is important
to not include commands as that may lead to link errors due to other
things we have already discarded.  In this case change things so that we
only build the right objects for SPL or non-SPL

Cc: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>
Signed-off-by: Tom Rini <trini@konsulko.com>