hwmon: (dme1737) cleanups

This patch cleans up and prepares the dme1737 driver for support of the sch311x
chips. (Almost) no functional changes.

- Replaced whitespaces with tabs.
- Removed empty lines.
- Added _i2c_ to names of functions that are strictly I2C related.
- Added 4 new functions: dme1737_create_files, dme1737_remove_files,
  dme1737_sio_enter, and dme1737_sio_exit.
- Added error messages in case client attach/detach fails.

Signed-off-by: Juerg Haefliger <juergh at gmail.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>