sixaxis: Fix compilation and various coding style issues

This fixes the following problems:

plugins/sixaxis.c:443:7: error: ‘version’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  if (!setup_device(fd, sysfs_path, name, source, vid, pid, version, type, adapter))
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
plugins/sixaxis.c:409:34: note: ‘version’ was declared here
  uint16_t bus, vid, pid, source, version;
                                  ^~~~~~~
plugins/sixaxis.c:443:7: error: ‘source’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  if (!setup_device(fd, sysfs_path, name, source, vid, pid, version, type, adapter))
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
plugins/sixaxis.c:409:26: note: ‘source’ was declared here
  uint16_t bus, vid, pid, source, version;
                          ^~~~~~
cc1: all warnings being treated as errors

And many instances of code going over 80 columns.
3 files changed