Configs: Migrate CONFIG_SYS_I2C_OMAP34XX to CONFIG_SYS_I2C_OMAP24XX

The driver is for all boards 24XX and up, so let's eliminate the
extra option called CONFIG_SYS_I2C_OMAP34XX since the driver checks
for CONFIG_OMAP34XX we don't need CONFIG_SYS_I2C_OMAP34XX.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>