staging: hv: Remove Ringbuffer from TODO line

Remove Ringbuffer work line item from TODO file.

The ring buffer in the Hyper-V Linux drivers is used to communicate with
the parent partition running Windows Server 2008 Hyper-V. The ring
buffer functionality on the Hyper-V Linux drivers is written to be
functionally compatible with the ring buffer functionality on the
Hyper-V Server. Consequently, it is not possible to make any changes
that might break the compatibility with server side ring buffer
implementation.
Signed-off-by: NHank Janssen <hjanssen@microsoft.com>
Signed-off-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/staging/hv/TODO

 TODO:
 	- fix remaining checkpatch warnings and errors
 	- use of /** when it is not a kerneldoc header
-	- remove RingBuffer.c to us in-kernel ringbuffer functions instead.
 	- audit the vmbus to verify it is working properly with the
 	  driver model
 	- convert vmbus driver interface function pointer tables