ARM: shmobile: koelsch: Enable SATA0 in r8a7791-koelsch.dts

This enables SATA0 in Koelsch device tree.
SATA1 is not available on Koelsch since
its pinmux configuration is fixed to PCIe.

Signed-off-by: Valentine Barshak <valentine.barshak@cogentembedded.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>