w83781d: Fix unchecked return status

w83781d: Fix unchecked return status

Add 2 attr-file groups (for base and model-specific attrs respectively),
create the base group with single call to sysfs_create_group,
check the return code on individual calls to device_create_file for each
of the model-specific attr-files.
Signed-off-by: Jim Cromie <jim.cromie@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>