xprtrdma: Update obsolete comment

Comment was made obsolete by commit 8cec3dba76a4 ("xprtrdma:
rpcrdma_regbuf alignment").

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
1 file changed