display: misc: Relocate save_display_log()/print_info() to reduce plugin duplication

display: misc: Relocate save_display_log()/print_info() to reduce plugin duplication

To move display-lock/lock-detector files to core, save_display_log, print_info functions are also relocated.
Because there is a dependence between files and functions.

This function is added to below display-misc.
void display_misc_save_display_log(const char *path);
-> This function is called when the poweroff notify, sighup situation
    or dbus method is called to save display log.

Change-Id: I8d8865aa3fc04ab3ac51e7e3106bdd3f42baf92e
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>