clk: introduce enable_count

As what Linux Kernel 5.3.0 provides when enable/disable clk,
there is an enable_count in clk_core_disable/enable. Introduce
enable_count to track the clk enable/disable count when
clk_enable/disable for CCF. And Initialize enable_count to 0 when
register the clk.

And clk tree dump with enable_count will be supported, it will
be easy for us to check the clk status with enable_count

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/include/clk.h b/include/clk.h
index 3ca2796..18b2e3c 100644
--- a/include/clk.h
+++ b/include/clk.h
@@ -61,6 +61,7 @@
 	struct udevice *dev;
 	long long rate;	/* in HZ */
 	u32 flags;
+	int enable_count;
 	/*
 	 * Written by of_xlate. In the future, we might add more fields here.
 	 */