linux-phytec-ti

PCI: dwc: designware: Make "num-ob-windows" dt property optional

Certain platforms like TI's K2G manages it's own outbound windows
making "num-ob-windows" useless in designware core. Make it optional
so that not having "num-ob-windows" is not a fatal error only if
outbound_atu callback is provided.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>