spl: dm: Kconfig: split OF_CONTROL and OF_PLATDATA between SPL and TPL

For the RK3368, we want to use OF_PLATDATA in TPL, but full OF_CONTROL
in SPL: this requires the introduction of a new family of
configuration options to decouple SPL_OF_CONTROL and SPL_OF_PLATDATA
from TPL.

Consequently, Makefile.spl needs to be adjusted to test for these
configuration items through the $(SPL_TPL_) macro instead of
hard-coding the SPL variant.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>