FreeBSD: Enable Direct IO by default

Commits 25eb538778, 178682506f, and 8dc452d907 resolve the remaining
known issues with Direct IO on FreeBSD. Enable it by default on all
platforms.

Signed-off-by: Brian Behlendorf <[email protected]>
Closes #16761

module/zfs/zfs_vnops.c

@@ -89,15 +89,8 @@ int zfs_bclone_wait_dirty = 1;
  * Enable Direct I/O. If this setting is 0, then all I/O requests will be
  * directed through the ARC acting as though the dataset property direct was
  * set to disabled.
- *
- * Disabled by default on FreeBSD until a potential range locking issue in
- * zfs_getpages() can be resolved.
  */
-#ifdef __FreeBSD__
-static int zfs_dio_enabled = 0;
-#else
 static int zfs_dio_enabled = 1;
-#endif
 
 /*
  * Strictly enforce alignment for Direct I/O requests, returning EINVAL