usb: host: max3421-hcd: Use module_spi_driver

module_spi_driver simplifies the code by eliminating
boilerplate code.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: David Mosberger <davidm@egauge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>