test: dm: clk_ccf: test ccf_clk_ops

Assign ccf_clk_ops to .ops of clk_ccf driver so that it can act as an
clk provider. Also add "#clock-cells=<1>" to its device tree node.

Add "i2c_root" to clk_test in the device tree and driver for testing.

Get "i2c_root" clock in CCF unit tests and add tests for it.

Signed-off-by: Yang Xiwen <forbidden405@outlook.com>
Reviewed-by: Sean Anderson <seanga2@gmail.com>
Link: https://lore.kernel.org/r/20231111-enable_count-v3-2-08a821892fa9@outlook.com
diff --git a/drivers/clk/clk_sandbox_ccf.c b/drivers/clk/clk_sandbox_ccf.c
index fedcdd4..38184e2 100644
--- a/drivers/clk/clk_sandbox_ccf.c
+++ b/drivers/clk/clk_sandbox_ccf.c
@@ -284,6 +284,7 @@
 U_BOOT_DRIVER(sandbox_clk_ccf) = {
 	.name = "sandbox_clk_ccf",
 	.id = UCLASS_CLK,
+	.ops = &ccf_clk_ops,
 	.probe = sandbox_clk_ccf_probe,
 	.of_match = sandbox_clk_ccf_test_ids,
 };