coresight: Doesn't save and restore ETMs state while CPU hot-plug

Doesn't save and restore ETMs state while CPU being offline and
online hot-plug. Since ETM driver can save and restore ETMs state
in hot-plug process. If JTAG driver save and restore ETMs state
as well, there could be some conflicts with ETM driver.

Change-Id: Ib4de3c0e3d0abb4cb15946fc444e0c1fc9188fd1
Signed-off-by: Tao,Zhang <taozha@codeaurora.org>