staging: mt29f_spinand: Use module_spi_driver

module_spi_driver removes the boilerplate code and simplifies it.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Henry Pan <hspan@micron.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>