USB: usbfs: remove double evaluation of usb_sndctrlpipe()

usb_sndctrlpipe() is evaluated in do_proc_control(), saved in a
variable, then evaluated again. Use the saved variable instead, to
match the use of usb_rcvctrlpipe().

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/20210521174027.GA116484@m.b4.vu


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>