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/MPC8544DS_defconfig b/configs/MPC8544DS_defconfig
index 3e75de7..457dfb1 100644
--- a/configs/MPC8544DS_defconfig
+++ b/configs/MPC8544DS_defconfig
@@ -28,5 +28,6 @@
 CONFIG_SCSI=y
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
+CONFIG_USB_EHCI_PCI=y
 CONFIG_USB_STORAGE=y
 CONFIG_OF_LIBFDT=y