arm: mvebu: turris_omnia: Signal error when sata/pcie DT mode

Show error message when DT file does not contain sata or pcie node which
should be explicitly disabled. This can happen when U-Boot code for finding
those nodes is incomplete or when those DT nodes are in different
unexpected location. In any case it is needed to know if DT not was not
explicitly disabled as it could mean that combo slots where setup
incorrectly.

Signed-off-by: Pali Rohár <pali@kernel.org>