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>
diff --git a/configs/uniphier_pro4_defconfig b/configs/uniphier_pro4_defconfig
index a7dcc56..ddc582d 100644
--- a/configs/uniphier_pro4_defconfig
+++ b/configs/uniphier_pro4_defconfig
@@ -32,4 +32,6 @@
 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