coresight: etm3x: Deal with CLAIM tag before and after accessing HW

This patch moves access to the CLAIM tag so that no modification to the HW
happens before and after the CLAIM operation has been carried.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>