usb: ehci: Convert CONFIG_USB_EHCI_PCI to Kconfig

This converts CONFIG_USB_EHCI_PCI to a Kconfig option, and updates
all boards that use it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/MPC8572DS_36BIT_defconfig b/configs/MPC8572DS_36BIT_defconfig
index 4a3a7e0..1c4ab11 100644
--- a/configs/MPC8572DS_36BIT_defconfig
+++ b/configs/MPC8572DS_36BIT_defconfig
@@ -27,5 +27,6 @@
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
+CONFIG_USB_EHCI_PCI=y
 CONFIG_USB_STORAGE=y
 CONFIG_OF_LIBFDT=y