mfd: twl4030: fix ELF section mismatch...

Since twl4030_probe is only called from functions in the init ELF
section, annotate it so.

Signed-off-by: Daniel J Blueman <daniel.blueman@gmail.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>