i2c-s3c2410: move to using platform idtable to match devices

Change to using platform id table to match either of the two supported
platform device names in the driver. This simplifies the driver init and
exit code

Note, log messages will now be prefixed with 's3c-i2c' instead of the
driver name, so output will be of the form of:

s3c-i2c s3c2440-i2c.0: slave address 0x10

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