ENGR00141399-2 iMX5x: add clock debug information

ENGR00141399-2 iMX5x: add clock debug information

Expose clock debug information to debugfs, which makes it easier for clock
system debug by using tools like powerdebug developed by Linaro power
management group.
For long term, this can go into common clock framework, but so far it depends
on the process of common clk API development. Once the common clk API is
ready in upstream, the clock debug information will be based on it too.
The implementation based on common clk API had also been finished and
reviewed with Jeremy.

ARM: iMX5x: fix clock debug enable_count error

Signed-off-by: Yong Shen <yong.shen@linaro.org>
Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Signed-off-by: Jason Chen <b02280@freescale.com>