arm64: dts: freescale: sl28: enable SATA support

With a newer bootloader SATA might be used in a mPCI slot using a mSATA
card. Enable the SATA controller on the Kontron K-Box LS-230-A which
comes with such a slot.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>