Merge tee_{core,uta}_trace.h into libutil

Merges tee_core_trace.h and tee_uta_trace.h into a common trace.h
in libutil. Since the trace functions now resides libutil they have
to rely on core and libutee to provide functions to print to the
log device.

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (QEMU virt platform)