ARM: OMAP1: fix omap_udc registration

omap_udc platform device is not registered properly anymore:
CONFIG_USB_GADGET_OMAP was deleted by 193ab2a6 (usb: gadget: allow
multiple gadgets to be built) already in v3.1.

Fix by using CONFIG_USB_OMAP instead. Tested on Nokia 770 by checking
that omap_udc is probed & working properly when built as a module.

Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Tony Lindgren <tony@atomide.com>
diff --git a/arch/arm/mach-omap1/include/mach/usb.h b/arch/arm/mach-omap1/include/mach/usb.h
index 753cd5c..45e5ac7 100644
--- a/arch/arm/mach-omap1/include/mach/usb.h
+++ b/arch/arm/mach-omap1/include/mach/usb.h
@@ -2,7 +2,7 @@
  * FIXME correct answer depends on hmc_mode,
  * as does (on omap1) any nonzero value for config->otg port number
  */
-#ifdef	CONFIG_USB_GADGET_OMAP
+#if IS_ENABLED(CONFIG_USB_OMAP)
 #define	is_usb0_device(config)	1
 #else
 #define	is_usb0_device(config)	0