Fixed below error/warnings

   sound/built-in.o: In function `rt5645_i2c_probe':
>> rt5645.c:(.text+0xe38f5): undefined reference to
>> `devm_regmap_init_i2c'
   sound/built-in.o: In function `rt5645_i2c_driver_exit':
>> rt5645.c:(.exit.text+0x60e): undefined reference to `i2c_del_driver'
   sound/built-in.o: In function `rt5645_i2c_driver_init':
>> rt5645.c:(.init.text+0x1a90): undefined reference to
>> `i2c_register_driver'
Signed-off-by: NFang, Yang A <yang.a.fang@intel.com>
Signed-off-by: NMark Brown <broonie@kernel.org>