usb: phy: generic: switch over to IS_ENABLED()

when checking if our generic PHY is enabled,
it's a lot easier to use IS_ENABLED() instead
of manually checking for it. While at that, also
remove the bogus defined(MODULE) at the end of
the line.
Signed-off-by: Felipe Balbi <balbi@ti.com>

include/linux/usb/usb_phy_generic.h

@@ -13,7 +13,7 @@ struct usb_phy_generic_platform_data {
 	int gpio_reset;
 };
 
-#if defined(CONFIG_NOP_USB_XCEIV) || (defined(CONFIG_NOP_USB_XCEIV_MODULE) && defined(MODULE))
+#if IS_ENABLED(CONFIG_NOP_USB_XCEIV)
 /* sometimes transceivers are accessed only through e.g. ULPI */
 extern struct platform_device *usb_phy_generic_register(void);
 extern void usb_phy_generic_unregister(struct platform_device *);