soc: nxp: rw6xx: add support for segger rtt

This change adds support for segger rtt, similar to other supported
soc's. This was lacking when evaluating tracing.

Without this addition the system fails to build, indicating that
HAS_SEGGER_RTT is missing. Adding CONFIG_HAS_SEGGER_RTT in prj.conf is
not allowed.

Signed-off-by: Bart De Vos <bart.devos@verhaert.com>