ENGR00271136 Fix build break when CONFIG_CLK_DEBUG is disabled

clk structure member name is defined only when CONFIG_CLK_DEBUG is enabled.
Hence need to encapsulate the code with this config.

Patch received from imx community:
https://community.freescale.com/thread/308482

Signed-off-by: xiongweihuang
Signed-off-by: Mahesh Mahadevan <Mahesh.Mahadevan@freescale.com>