We now have the CONFIG_SPL_DM for code within SPL to toggle caring about
DM or not.  Without this change platforms that do enable CONFIG_DM but
not CONFIG_SPL_DM may be broken (such as OMAP5).

Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Signed-off-by: Tom Rini <trini@konsulko.com>