Kconfig: USB: Migrate CONFIG_USB_EHCI_HCD users to Kconfig

Migrate the rest of the users of CONFIG_USB_EHCI_HCD over to Kconfig.
For a few SoCs, imply or default y this if USB is enabled.  In some
cases we had not already migrated to CONFIG_USB so do that as well.

Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 0033c35..01e9008 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -32,6 +32,7 @@
 	select CREATE_ARCH_SYMLINK
 	select SYS_FSL_DDR
 	select SYS_FSL_DDR_BE
+	imply USB_EHCI_HCD if USB
 
 config MPC86xx
 	bool "MPC86xx"