mfd: Fix section mismatch in da903x

The subdevice removal functions are marked __devexit but are referenced
from the error handling path when probing so are needed even when
__devexit functions are removed.

Signed-off-by: Mark Brown <broonie@sirena.org.uk>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@openedhand.com>