staging: rtl8188eu: set pipe only once

Set the pipe for reading or writing in usbctrl_vendorreq only once. There's
no need to set it again for every retry.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210407170531.29356-5-martin@kaiser.cx


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