samples: tracing: Add filter for uart tests
samples: tracing: Add filter for uart tests

Add a filter to make sure devicetree chosen node has
property 'zephyr,tracing-uart' set in it.

Signed-off-by: Kumar Gala <383ef5577c6e1178b93f59ec8d0936f76d2a98c4@kernel.org>

zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr