locks: get rid of WE_CAN_BREAK_LSLK_NOW dead code

As Bruce points out, there's no compelling reason to change /proc/locks
output at this point. If we did want to do this, then we'd almost
certainly want to introduce a new file to display this info (maybe via
debugfs?).

Let's remove the dead WE_CAN_BREAK_LSLK_NOW ifdef here and just plan to
stay with the legacy format.

Reported-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>