usb: gadget: Add NO_DMA dummies for DMA mapping API

Add dummies for usb_gadget_{,un}map_request{,_by_dev}(), to allow
compile-testing if NO_DMA=y.

This prevents the following from showing up later:

    ERROR: "usb_gadget_unmap_request_by_dev" [drivers/usb/renesas_usbhs/renesas_usbhs.ko] undefined!
    ERROR: "usb_gadget_map_request_by_dev" [drivers/usb/renesas_usbhs/renesas_usbhs.ko] undefined!
    ERROR: "usb_gadget_map_request" [drivers/usb/mtu3/mtu3.ko] undefined!
    ERROR: "usb_gadget_unmap_request" [drivers/usb/mtu3/mtu3.ko] undefined!
    ERROR: "usb_gadget_map_request" [drivers/usb/gadget/udc/renesas_usb3.ko] undefined!
    ERROR: "usb_gadget_unmap_request" [drivers/usb/gadget/udc/renesas_usb3.ko] undefined!

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

include/linux/usb/gadget.h

@@ -805,6 +805,7 @@ int usb_otg_descriptor_init(struct usb_gadget *gadget,
 
 /* utility to simplify map/unmap of usb_requests to/from DMA */
 
+#ifdef	CONFIG_HAS_DMA
 extern int usb_gadget_map_request_by_dev(struct device *dev,
 		struct usb_request *req, int is_in);
 extern int usb_gadget_map_request(struct usb_gadget *gadget,
@@ -814,6 +815,17 @@ extern void usb_gadget_unmap_request_by_dev(struct device *dev,
 		struct usb_request *req, int is_in);
 extern void usb_gadget_unmap_request(struct usb_gadget *gadget,
 		struct usb_request *req, int is_in);
+#else /* !CONFIG_HAS_DMA */
+static inline int usb_gadget_map_request_by_dev(struct device *dev,
+		struct usb_request *req, int is_in) { return -ENOSYS; }
+static inline int usb_gadget_map_request(struct usb_gadget *gadget,
+		struct usb_request *req, int is_in) { return -ENOSYS; }
+
+static inline void usb_gadget_unmap_request_by_dev(struct device *dev,
+		struct usb_request *req, int is_in) { }
+static inline void usb_gadget_unmap_request(struct usb_gadget *gadget,
+		struct usb_request *req, int is_in) { }
+#endif /* !CONFIG_HAS_DMA */
 
 /*-------------------------------------------------------------------------*/