core_ctl: Take state_lock while preparing the global_state

global_state file output is prepared by reading the members of CPU
and cluster data structures. These members are updated under state_lock,
so acquire the same lock while preparing the output.

Change-Id: I8cb3ca6f9100a24f0bc9b293d364ad6aa8aabefb
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>