coresight-etm4x: Read only access to the main management registers

Having access to the ETMv4 management registers is very useful as they
give meaningful information on how the IP block has been configured at
synthesis time.

Change-Id: Ieaed70257458e94151ec665a210e46395ac95c7a
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: a467dae11d57c60dabf9f85d7691e6ce097fc424
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Shashank Mittal <mittals@codeaurora.org>