The old usb_control_msg() let the caller handle the error and also did not
account for partial reads.  Since these are now considered harmful, move the
driver over to usb_control_msg_recv/send() calls.

Added small note about why set_registers() can't be used to substitute
set_register().
Signed-off-by: Petko Manolov <petko.manolov@konsulko.com>
Acked-by: David S. Miller <davem@davemloft.net>
Link: https://lore.kernel.org/r/20200927124909.16380-2-petko.manolov@konsulko.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>