clk: rockchip: clk-out: Add CLK_IGNORE_UNUSED flag

It's used for compatible for old style mclk reference
which do not use the "mclkout_x".

The clk framework will disable all unused clk after
system boot done. in this situation, it is failed to
output mclk with old style DT, because "mclkout_x"
was disabled by framework.

We add CLK_IGNORE_UNUSED flag to clk-out to allow old
style usage still work well.

Suggest to drop this flag for totally new SDK or SoCs
in the future. at the moment, we still need this flag.

Fixes: b3cfac5e37 ("clk: rockchip: Add support for clk input / output switch")

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Change-Id: I9d0a6b04637d055bc8beb0a03a630804108d4b28

drivers/clk/rockchip/clk-out.c

@@ -50,7 +50,7 @@ static int rockchip_clk_out_probe(struct platform_device *pdev)
 
 	pm_runtime_enable(dev);
 
-	hw = clk_hw_register_gate(dev, clk_name, parent_name, CLK_SET_RATE_PARENT,
+	hw = clk_hw_register_gate(dev, clk_name, parent_name, CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED,
 				  reg, shift, clk_gate_flags, &clk_out_lock);
 	if (IS_ERR(hw)) {
 		ret = -EINVAL;