ARM: dts: sun8i-r40-bananapi-m2-berry: Enable AHCI

Enable ahci node for BPI-M2-Berry, this would require since
we have DM_SCSI enabled on the respective SoC.

Unable to sync the same node from Linux, since the similar change
is still in Linux ML.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>