coresight-etm3x: use module_amba_driver to simplify the code

Using function "module_amba_driver()" makes the code simpler by
eliminating boilerplate code.

Wei Yongjun sent out a set of patches addressing those in all the
coresight driver but missed ETMv3.

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