xen-blkback/sysfs: Move the parameters for the persistent grant features

to a testing subdirectory (as this value should not be baked
for the life-time) and also in an appropiate file.

Also modified the introduction Linux version from 3.10 to 3.11.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Documentation/ABI/stable/sysfs-bus-xen-backend

@@ -73,21 +73,3 @@ KernelVersion:	3.0
 Contact:	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
 Description:
                 Number of sectors written by the frontend.
-
-What:           /sys/module/xen_blkback/parameters/max_buffer_pages
-Date:           March 2013
-KernelVersion:  3.10
-Contact:        Roger Pau Monné <roger.pau@citrix.com>
-Description:
-                Maximum number of free pages to keep in each block
-                backend buffer.
-
-What:           /sys/module/xen_blkback/parameters/max_persistent_grants
-Date:           March 2013
-KernelVersion:  3.10
-Contact:        Roger Pau Monné <roger.pau@citrix.com>
-Description:
-                Maximum number of grants to map persistently in
-                blkback. If the frontend tries to use more than
-                max_persistent_grants, the LRU kicks in and starts
-                removing 5% of max_persistent_grants every 100ms.

Documentation/ABI/testing/sysfs-driver-xen-blkback

@@ -0,0 +1,17 @@
+What:           /sys/module/xen_blkback/parameters/max_buffer_pages
+Date:           March 2013
+KernelVersion:  3.11
+Contact:        Roger Pau Monné <roger.pau@citrix.com>
+Description:
+                Maximum number of free pages to keep in each block
+                backend buffer.
+
+What:           /sys/module/xen_blkback/parameters/max_persistent_grants
+Date:           March 2013
+KernelVersion:  3.11
+Contact:        Roger Pau Monné <roger.pau@citrix.com>
+Description:
+                Maximum number of grants to map persistently in
+                blkback. If the frontend tries to use more than
+                max_persistent_grants, the LRU kicks in and starts
+                removing 5% of max_persistent_grants every 100ms.