i2c: Include linux/of.h header

'of_match_ptr' is defined in linux/of.h. Include it explicitly to
avoid build breakage in the future.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --cc drivers/i2c/busses/i2c-gpio.c
Simple merge

diff --cc drivers/i2c/busses/i2c-pnx.c
Simple merge

diff --cc drivers/i2c/busses/i2c-s3c2410.c
Simple merge

diff --cc drivers/i2c/busses/i2c-xiic.c
Simple merge

diff --cc drivers/i2c/muxes/i2c-mux-pinctrl.c
Simple merge