I2C: OMAP1/OMAP2+: add flags field to omap i2c platform data

OMAP I2C driver can access the configuration flags through
its platform data.

Cc: patches@linaro.org
Cc: Ben Dooks <ben-linux@fluff.org>
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andy Green <andy.green@linaro.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>