usb: gadget: udc: renesas_usb3: Fix return value of usb3_write_pipe()

usb: gadget: udc: renesas_usb3: Fix return value of usb3_write_pipe()

commit 447b8a01b84f048d93d43bfe1fcaa4fcc56595cc upstream.

This patch fixes an issue that this driver cannot go status stage
in control read when the req.zero is set to 1 and the len in
usb3_write_pipe() is set to 0. Otherwise, if we use g_ncm driver,
usb enumeration takes long time (5 seconds or more).

Fixes: 746bfe63bba3 ("usb: gadget: renesas_usb3: add support for Renesas USB3.0 peripheral controller")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>