clk: clk-gate: Resolve parent clock by name

Use clock-names property which is accessible via parent clock OF node
to look up the parent clock by name instead of depending on unreliable
global clock name to perform look up.

Signed-off-by: Marek Vasut <marex@denx.de>

drivers/clk/clk-gate.c

@@ -149,7 +149,8 @@ struct clk *clk_register_gate(struct udevice *dev, const char *name,
 	clk = &gate->clk;
 	clk->flags = flags;
 
-	ret = clk_register(clk, UBOOT_DM_CLK_GATE, name, parent_name);
+	ret = clk_register(clk, UBOOT_DM_CLK_GATE, name,
+		clk_resolve_parent_clk(dev, parent_name));
 	if (ret) {
 		kfree(gate);
 		return ERR_PTR(ret);