i2c-powermac: Fix section for probe and remove functions

__devexit for i2c_powermac_probe is obviously wrong.  In the definition
of struct platform_driver i2c_powermac_driver the remove function
i2c_powermac_remove is wrapped in __devexit_p, so it should be defined
using __devexit.

Signed-off-by: Uwe Kleine-Koenig <ukleinek@informatik.uni-freiburg.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Jean Delvare <khali@linux-fr.org>