Description of problem:
=======================
event though bitrot is not enabled on volume it is setting xattr bit-rot.signature and bit-rot.version

Version-Release number of selected component (if applicable):
=============================================================
0.803.gitf64666f.el6.x86_64

How reproducible:
=================
always

Steps to Reproduce:
===================
1. create and mount volume.
Volume Name: tier_distrep
Type: Distributed-Replicate
Volume ID: ad81ef54-70ec-41f2-800c-17e5025acb26
Status: Started
Number of Bricks: 5 x 2 = 10
Transport-type: tcp
Bricks:
Brick1: rhs-client38:/pavanbrick2/tier_distrep/hb2m
Brick2: rhs-client37:/pavanbrick2/tier_distrep/hb2
Brick3: rhs-client37:/pavanbrick2/tier_distrep/hb1m
Brick4: rhs-client44:/pavanbrick2/tier_distrep/hb1
Brick5: rhs-client44:/pavanbrick1/tier_distrep/b1
Brick6: rhs-client37:/pavanbrick1/tier_distrep/b1m
Brick7: rhs-client37:/pavanbrick1/tier_distrep/b2
Brick8: rhs-client38:/pavanbrick1/tier_distrep/b2m
Brick9: rhs-client44:/pavanbrick1/tier_distrep/b3m
Brick10: rhs-client38:/pavanbrick1/tier_distrep/b3

2. create few files.
3. verify xattr for files in backend

[root@rhs-client44 try]# getfattr -d -m . -e hex /pavanbrick1/tier_distrep/b1/f12
getfattr: Removing leading '/' from absolute path names
# file: pavanbrick1/tier_distrep/b1/f12
trusted.gfid=0x9142b9dfe68c47149d95dfd037177723
trusted.glusterfs.bit-rot.signature=0xff000000000000000000000000000000
trusted.glusterfs.bit-rot.version=0x010000000000000055152f6c000566ef


Actual results:
===============
even though bitrot is not enabled on volume it is setting xattr bit-rot.signature and bit-rot.version