The usb_control_msg_send() call can handle data on the stack, as well as
returning an error if a "short" write happens, so move the driver over
to using that call instead.  This ends up removing a helper function
that is no longer needed.

Cc: Jaroslav Kysela <perex@perex.cz>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20200914153756.3412156-7-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>