phy: phy-brcm-usb: Fix two DT properties to match bindings doc

Change "brcm,has_xhci" and "brcm,has_eohci" device tree properties
to the preferred "brcm,has-xhci" and "brcm,has-eohci". This also
matches the existing device tree bindings document.

Fixes: 49859e55 ("phy: usb: phy-brcm-usb: Add Broadcom STB USB phy driver")
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>