IB/rdmavt: Don't vfree a kzalloc'ed memory region

The userspace memory region 'mr' is allocated with kzalloc in
__rvt_alloc_mr  however it is incorrectly being freed with vfree in
__rvt_free_mr. Fix this by using kfree to free it.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rdmavt/mr.c

@@ -294,7 +294,7 @@ static void __rvt_free_mr(struct rvt_mr *mr)
 {
 	rvt_deinit_mregion(&mr->mr);
 	rvt_free_lkey(&mr->mr);
-	vfree(mr);
+	kfree(mr);
 }
 
 /**