ARM: dts: NSP: Disable AHCI controller for HR NSP boards

The AHCI controller is currently enabled for all of these boards:
bcm958623hr and bcm958625hr would result in a hard hang on boot that we
cannot get rid of. Since this does not appear to have an easy and simple
fix, just disable the AHCI controller for now until this gets resolved.

Fixes: 70725d6e ("ARM: dts: NSP: Enable SATA on bcm958625hr")
Fixes: d454c376 ("ARM: dts: NSP: Add new DT file for bcm958623hr")
Acked-by: Jon Mason <jon.mason@broadcom.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>