Kconfig: OMAP: USB: Migrate CONFIG_USB_EHCI_OMAP to Kconfig

Follow the exiting logic for the i.MX options when migrating this
option.

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/eco5pk_defconfig b/configs/eco5pk_defconfig
index a6de0b2..61ac94b 100644
--- a/configs/eco5pk_defconfig
+++ b/configs/eco5pk_defconfig
@@ -25,5 +25,6 @@
 CONFIG_SYS_NS16550=y
 CONFIG_USB=y
 CONFIG_USB_EHCI_HCD=y
+# CONFIG_USB_EHCI_OMAP is not set
 CONFIG_USB_STORAGE=y
 CONFIG_OF_LIBFDT=y