dt-bindings: ata: Document BCM7216 AHCI controller compatible

The BCM7216 AHCI controller makes use of a specific reset controller
line/name, document the compatible string and the optional reset
properties.

Reviewed-by: Rob Herring <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Signed-off-by: Florian Fainelli <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

Documentation/devicetree/bindings/ata/brcm,sata-brcm.txt

···
 
 Required properties:
 - compatible         : should be one or more of
+			"brcm,bcm7216-ahci"
 			"brcm,bcm7425-ahci"
 			"brcm,bcm7445-ahci"
 			"brcm,bcm-nsp-ahci"
···
 - reg                : register mappings for AHCI and SATA_TOP_CTRL
 - reg-names          : "ahci" and "top-ctrl"
 - interrupts         : interrupt mapping for SATA IRQ
+
+Optional properties:
+
+- reset: for "brcm,bcm7216-ahci" must be a valid reset phandle
+  pointing to the RESCAL reset controller provider node.
+- reset-names: for "brcm,bcm7216-ahci", must be "rescal".
 
 Also see ahci-platform.txt.