coresight: etm3x: Fix cpulocked warning on cpuhp

coresight: etm3x: Fix cpulocked warning on cpuhp

When changes [1] and [2] have been applied to the driver etm4x, the
same modifications have been also collapsed in [3] and applied in
one shot to the driver etm3x.
While doing this, the driver etm3x has not been aligned to etm4x on
the use of non cpuslocked version of cpuhp callback setup APIs.

The current code triggers two run-time warnings when the kernel is
compiled with CONFIG_PROVE_LOCKING=y.

Use non cpuslocked version of cpuhp callback setup APIs in driver
etm3x, aligning it to the driver etm4x.

[1] commit 2d1a8bfb61ec ("coresight: etm4x: Fix etm4_count race by
                          moving cpuhp callbacks to init")
[2] commit 22a550a306ad ("coresight: etm4x: Allow etm4x to be built
                          as a module")
[3] commit 97fe626ce64c ("coresight: etm3x: Allow etm3x to be built
                          as a module")

Fixes: 97fe626ce64c ("coresight: etm3x: Allow etm3x to be built as a module")
Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20260108152427.357379-1-antonio.borneo@foss.st.com