[ARM] S3C24XX: Reduce code lineage of gpiolib.c

All the s3c24xx gpiolib chips share the same get/set
calls and all but one bank shares the same calls for
.direction_input and .direction_output methods.

Change the initialisation process to use an new call
to register the chips that fills in any blank calls
with the default values to avoid having to fill them
in the structure initialisers.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>