performance profile support

Many device trees support the recovery.perf.mode property to
set various core frequencies and online/offline mode. TWRP is
highly threaded, and support for multiple cores on many operations
dramatically recudes the time, e.g., backups, zip flashes, etc.

p2: removed user notifications

Change-Id: I957b8ca40b241c0af0471327eeb329cce1816017
diff --git a/twrp-functions.hpp b/twrp-functions.hpp
index c46738e..de14d94 100644
--- a/twrp-functions.hpp
+++ b/twrp-functions.hpp
@@ -87,6 +87,8 @@
 	static int Set_Brightness(std::string brightness_value); // Well, you can read, it does what it says, passing return int from TWFunc::Write_File ;)
 	static bool Toggle_MTP(bool enable);                                        // Disables MTP if enable is false and re-enables MTP if enable is true and it was enabled the last time it was toggled off
+	static void SetPerformanceMode(bool mode); // support recovery.perf.mode
 	static void Copy_Log(string Source, string Destination);