Use the correct lock to protect members in PolicyControl

Members in PolicyControl can be accessed by multiple threads via the
public functions called by PhoneWindowManager. Most of the functions
are called with the window-manager-lock held, but reloadFromSetting()
is an exception.

In this patch, we acquire the window-manager-lock before calling
reloadFromSetting() to ensure accessing the members with the same
lock held.

Change-Id: I54ac5cab2a2d74c568fa96145f7a6741c6d99e36