ASoC: Intel: Skylake: Add I2C depends for SKL machine

The i2c is dependency for the i2c codec drivers, so machine should depend on
i2c. WIthout this we get build failures if I2C is not selected

   sound/soc/codecs/rl6347a.c: In function 'rl6347a_hw_write':
>> sound/soc/codecs/rl6347a.c:66:8: error: implicit declaration of function
>> 'i2c_master_send' [-Werror=implicit-function-declaration]
     ret = i2c_master_send(client, data, 4);
           ^
   sound/soc/codecs/rl6347a.c: In function 'rl6347a_hw_read':
>> sound/soc/codecs/rl6347a.c:114:8: error: implicit declaration of function
>> 'i2c_transfer' [-Werror=implicit-function-declaration]
     ret = i2c_transfer(client->adapter, xfer, 2);

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>