mmc: davinci: dont' use module_platform_driver_probe()

This changes module_platform_driver_probe() to module_platform_driver()
in the TI DaVinci MMC driver.

On device tree systems, we can get a -EPROBE_DEFER when using a pinmux
for the CD GPIO, which results in the driver never loading because
module_platform_driver_probe() prevents it from being re-probed.

So, we replace module_platform_driver_probe() with
module_platform_driver() and removed the __init attributes accordingly.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>