coresight: add remote etm driver support in upstream code

Add remote etm driver in upstream implementation of Coresight
driver.
This change copies coresight-remote-etm.c file from
drivers/coresight (commit c1fe9ac38d93 ("input: touchscreen:
correct function and variable names in ITE tech driver")) to
driver/hwtracing/coresight directory.

Change-Id: I77a1aaf10aaf3f3010ab19d5878bb53dcc504c29
Signed-off-by: Shashank Mittal <mittals@codeaurora.org>
Signed-off-by: Satyajit Desai <sadesai@codeaurora.org>