coresight: etm3x: breaking down sysFS status interface

SysFS rules stipulate that only one value can be conveyed per
file.  As such splitting the "status" interface in individual files.

This is also useful for user space applications - that way they can
probe each file individually rather than having to parse a list of entries.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>