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/configs/MPC8349ITX_LOWBOOT_defconfig b/configs/MPC8349ITX_LOWBOOT_defconfig
index a97ce25..4a7ff1b 100644
--- a/configs/MPC8349ITX_LOWBOOT_defconfig
+++ b/configs/MPC8349ITX_LOWBOOT_defconfig
@@ -20,5 +20,6 @@
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
+CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_STORAGE=y
 CONFIG_OF_LIBFDT=y