docs: i2c: dev-interface: adapt to new filenames of the i2c core

The I2C core files were renamed, adapt the textfile to it.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

Documentation/i2c/dev-interface

@@ -191,7 +191,7 @@ checking on future transactions.)
 4* Other ioctl() calls are converted to in-kernel function calls by
 i2c-dev. Examples include I2C_FUNCS, which queries the I2C adapter
 functionality using i2c.h:i2c_get_functionality(), and I2C_SMBUS, which
-performs an SMBus transaction using i2c-core.c:i2c_smbus_xfer().
+performs an SMBus transaction using i2c-core-smbus.c:i2c_smbus_xfer().
 
 The i2c-dev driver is responsible for checking all the parameters that
 come from user-space for validity. After this point, there is no
@@ -200,13 +200,13 @@ and calls that would have been performed by kernel I2C chip drivers
 directly. This means that I2C bus drivers don't need to implement
 anything special to support access from user-space.
 
-5* These i2c-core.c/i2c.h functions are wrappers to the actual
-implementation of your I2C bus driver. Each adapter must declare
-callback functions implementing these standard calls.
-i2c.h:i2c_get_functionality() calls i2c_adapter.algo->functionality(),
-while i2c-core.c:i2c_smbus_xfer() calls either
+5* These i2c.h functions are wrappers to the actual implementation of
+your I2C bus driver. Each adapter must declare callback functions
+implementing these standard calls. i2c.h:i2c_get_functionality() calls
+i2c_adapter.algo->functionality(), while
+i2c-core-smbus.c:i2c_smbus_xfer() calls either
 adapter.algo->smbus_xfer() if it is implemented, or if not,
-i2c-core.c:i2c_smbus_xfer_emulated() which in turn calls
+i2c-core-smbus.c:i2c_smbus_xfer_emulated() which in turn calls
 i2c_adapter.algo->master_xfer().
 
 After your I2C bus driver has processed these requests, execution runs