ARM: uniphier: switch over to generic EHCI driver

The UniPhier EHCI driver (drivers/usb/host/ehci-uniphier.c) does
nothing special but set the base address and handle reset/clock.

Since commit 4feefdcfe916 ("usb: add clock support for generic EHCI"),
the generic one (drivers/usb/host/ehci-generic.c) can do those, too.

We no longer need to stick to the dedicated driver.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/configs/uniphier_ld4_sld8_defconfig b/configs/uniphier_ld4_sld8_defconfig
index ee3cbad..535f96f 100644
--- a/configs/uniphier_ld4_sld8_defconfig
+++ b/configs/uniphier_ld4_sld8_defconfig
@@ -27,5 +27,7 @@
 CONFIG_SPL_PINCTRL=y
 CONFIG_UNIPHIER_SERIAL=y
 CONFIG_USB=y
+CONFIG_DM_USB=y
 CONFIG_USB_EHCI_HCD=y
+CONFIG_USB_EHCI_GENERIC=y
 CONFIG_USB_STORAGE=y