mfd: Fix section mismatch warning for da9052-spi

Add __devinit annotation for da9052_spi_probe to fix below build warning:

WARNING: drivers/built-in.o(.text+0x349b4): Section mismatch in reference from the function da9052_spi_probe() to the function .devinit.text:da9052_device_init()
The function da9052_spi_probe() references
the function __devinit da9052_device_init().
This is often because da9052_spi_probe lacks a __devinit
annotation or the annotation of da9052_device_init is wrong.

Also add __devexit annotation for da9052_spi_remove because we have
__devexit_p around it in the remove callback.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>