coresight: tmc: let runtime PM handle core clock

This uses runtime PM to manage the PCLK ("amba_pclk") instead
of screwing around with the framework by going in and taking
a copy from the amba device. The amba bus core will unprepare
and disable the clock when the device is unused when
CONFIG_PM is selected, else the clock will be always on.

Prior to this patch, as the AMBA primecell bus code enables
the PCLK, it would be left on after probe as
the clk_prepare_enable() and clk_disable_unprepare() was
called and thus just increase and decreas the refcount by
one, without it reaching zero and actually disabling the
clock. Now the runtime PM callbacks will make sure the PCLK
is properly disabled after probe.

Change-Id: I06e3a35adf4a9b8bb57c196ea2a0283a2321edda
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: 32398ef6f4745b2098d93f32e2c89e0286ab45fe
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Shashank Mittal <mittals@codeaurora.org>