mtip32xx: Add new sysfs entry 'status'

* Add support for detecting the following device status
        - write protect
        - over temp (thermal shutdown)
* Add new sysfs entry 'status', possible values - online, write_protect, thermal_shutdown
* Add new file 'sysfs-block-rssd' to document ABI (Reported-by: Greg Kroah-Hartman)

Signed-off-by: Asai Thambi S P <asamymuthupa@micron.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Documentation/ABI/testing/sysfs-block-rssd

@@ -0,0 +1,18 @@
+What:           /sys/block/rssd*/registers
+Date:           March 2012
+KernelVersion:  3.3
+Contact:        Asai Thambi S P <asamymuthupa@micron.com>
+Description:    This is a read-only file. Dumps below driver information and
+                hardware registers.
+                    - S ACTive
+                    - Command Issue
+                    - Allocated
+                    - Completed
+                    - PORT IRQ STAT
+                    - HOST IRQ STAT
+
+What:           /sys/block/rssd*/status
+Date:           April 2012
+KernelVersion:  3.4
+Contact:        Asai Thambi S P <asamymuthupa@micron.com>
+Description:   This is a read-only file. Indicates the status of the device.