dt-bindings: ata: sata-brcm: Apply common AHCI schema

The Broadcom SATA controller is obviously based on the AHCI standard. The
device driver uses the kernel AHCI library to work with it. Therefore we
can be have a more thorough DT-bindings evaluation by referring to the
AHCI-common schema instead of using the more relaxed SATA-common one.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>