ARM: uniphier: enable Generic EHCI driver for Pro4 SoC

This SoC is equipped with two EHCI cores and two xHCI cores.
Enable the generic EHCI driver for the former.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

configs/uniphier_pro4_defconfig

@@ -32,4 +32,6 @@ CONFIG_PINCTRL=y
 CONFIG_SPL_PINCTRL=y
 CONFIG_USB=y
 CONFIG_USB_XHCI_HCD=y
+CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI_GENERIC=y
 CONFIG_USB_STORAGE=y