usb: renesas_usbhs: fix DMA build by including dma-mapping.h

Include dma-mapping.h to fix build of the renesas_usbhs driver

CC      drivers/usb/renesas_usbhs/mod_gadget.o
drivers/usb/renesas_usbhs/mod_gadget.c: In function 'usbhsg_dma_map':
drivers/usb/renesas_usbhs/mod_gadget.c:190: error: implicit declaration of function 'dma_map_single'
drivers/usb/renesas_usbhs/mod_gadget.c:192: error: implicit declaration of function 'dma_sync_single_for_device'
drivers/usb/renesas_usbhs/mod_gadget.c:196: error: implicit declaration of function 'dma_mapping_error'
drivers/usb/renesas_usbhs/mod_gadget.c: In function 'usbhsg_dma_unmap':
drivers/usb/renesas_usbhs/mod_gadget.c:217: error: implicit declaration of function 'dma_unmap_single'
drivers/usb/renesas_usbhs/mod_gadget.c:219: error: implicit declaration of function 'dma_sync_single_for_cpu'
make[5]: *** [drivers/usb/renesas_usbhs/mod_gadget.o] Error 1
make[4]: *** [drivers/usb/renesas_usbhs] Error 2

Reported-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>