dt-bindings: spi: Add bcm63xx-hsspi controller support

Bring the device tree binding document from Linux to u-boot

Port from linux patches:
Link: https://lore.kernel.org/r/20230207065826.285013-2-william.zhang@broadcom.com
Link: https://lore.kernel.org/r/20230207065826.285013-3-william.zhang@broadcom.com


Signed-off-by: William Zhang <william.zhang@broadcom.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>