The commit 2d4aa21a ("usb: gadget: udc: renesas_usb3: add support
for dedicated DMAC") has a bug in the renesas_usb3_dma_free_prd().
The size of dma_free_coherent() should be the same with dma_alloc_coherent()
Otherwise, this code causes a WARNING by mm/page_alloc.c when
renesas_usb3_dma_free_prd() is called. So, this patch fixes it.

Fixes: 2d4aa21a ("usb: gadget: udc: renesas_usb3: add support for dedicated DMAC")
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>