clk: gate: support sandbox

Introduce io_gate_val for sandbox clk gate test usage

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index b954773..02ff1a3 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -75,6 +75,9 @@
 	void __iomem	*reg;
 	u8		bit_idx;
 	u8		flags;
+#if CONFIG_IS_ENABLED(SANDBOX_CLK_CCF)
+	u32		io_gate_val;
+#endif
 };
 
 #define to_clk_gate(_clk) container_of(_clk, struct clk_gate, clk)