There is no need to have a lock around calls to i2c_master_send() and
i2c_master_recv() as they are not issued concurrently and they are not
sharing any buffers. Also there is no need for command_mutex as all
commands are issued sequentially.

Remove both.

Tested-by: Andreas Kemnade <andreas@kemnade.info> # Tolino Shine2HD
Link: https://lore.kernel.org/r/20240824055047.1706392-7-dmitry.torokhov@gmail.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>