atmel/spi: fix missing probe

Commit 940ab889 "drivercore: Add helper macro for platform_driver boilerplate"
converted this driver to use module_platform_driver, but due to the use
of platform_driver_probe(), this resulted in the call to atmel_spi_probe being
lost. Place the call to this function into the driver structure.

fix section missmatch

atmel_spi_probe is marked __init where it's supposed to be __devinit
atmel_spi_remove is marked __exit where it's supposed to be __devexit

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>