ARM: dts: omap4-sdp: Add I2c pinctrl data

Booting 3.8-rc6 on omap 4430sdp results in the following error

omap_i2c 48070000.i2c: did not get pins for i2c error: -19
[    1.024261] omap_i2c 48070000.i2c: bus 0 rev0.12 at 100 kHz
[    1.030181] omap_i2c 48072000.i2c: did not get pins for i2c error: -19
[    1.037384] omap_i2c 48072000.i2c: bus 1 rev0.12 at 400 kHz
[    1.043762] omap_i2c 48060000.i2c: did not get pins for i2c error: -19
[    1.050964] omap_i2c 48060000.i2c: bus 2 rev0.12 at 100 kHz
[    1.056823] omap_i2c 4807a000.i2c: did not get pins for i2c error: -19
[    1.064025] omap_i2c 4807a000.i2c: bus 3 rev0.12 at 400 kHz

This happens because omap4 dts file is not adapted to use i2c through pinctrl
framework. Populating i2c pinctrl data to get rid of the error.

Tested on omap4430 sdp with 3.8-rc6 kernel.

Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Reported-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>