coresight-tmc: Add support of pcie mode

Add pcie mode to tmc-etr to support diag over stm over pcie. When
pcie mode is enabled, etr data will be written to qdss mhi out channel.

Change-Id: Ibca55f9221ff460a7d473f23cc05c22125e85961
Signed-off-by: Mao Jinlong <jinlmao@codeaurora.org>