The RK3399-Q7 requires DM regulator support in SPL, so we can use the
regulator framework to reenable the eMMC and SPI, if these had been
turned of by the BIOS_DISABLE signal.

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