Fix build warnings due to struct i2c_board_info in <mach/platform.h>

Patch "5311/1: add core support for built in i2c bus" is causing 11 of
39 the build warnings with Kautobuild for ep93xx_defconfig on kernel
2.6.29-rc5-git4.  This patch fixes it.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>