UPSTREAM: coresight: tmc: Cleanup operation mode handling

The mode of operation of the TMC tracked in drvdata->mode is defined
as a local_t type. This is always checked and modified under the
drvdata->spinlock and hence we don't need local_t for it and the
unnecessary synchronisation instructions that comes with it. This
change makes the code a bit more cleaner.

Also fixes the order in which we update the drvdata->mode to
CS_MODE_DISABLED. i.e, in tmc_disable_etX_sink we change the
mode to CS_MODE_DISABLED before invoking tmc_disable_etX_hw()
which in turn depends on the mode to decide whether to dump the
trace to a buffer.

Applies on mathieu's coresight/next tree [1]

https://git.linaro.org/kernel/coresight.git

 next

Reported-by: Venkatesh Vivekanandan <venkatesh.vivekanandan@broadcom.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 297ab90f15f6222408380bbf4e8cbff57b02060d)

Change-Id: I5f217d87f2e3a3e18764c1b5f909c88bf1a9dc91