i2c-s3c2410: Fix bug in releasing driver

When compiled as a module, the i2c-s3c2410 driver does not
free either the IRQ or the i2c adapter it attached to the system.

As part of this fix, move to the usual kernel style
of freeing items as part of the probe error path
making the remove process easier.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Jean Delvare <khali@linux-fr.org>