Kernel: Fix sse state saving

This was broken when I added SMP support. This patch makes sse kind of
dumb as it is saved and restored on every interrupt, but now it at least
works properly... I'll have to look into how sse can get optimized
nicely with SMP. Simple way would be pinning each thread to a specific
processor and doing pretty much what I had before, but sse thread saved
in processor rather than static global.

kernel/include/kernel/Thread.h

@@ -82,7 +82,6 @@ namespace Kernel
 #if __enable_sse
 		void save_sse();
 		void load_sse();
-		static Thread* sse_thread();
 #endif
 
 		void add_mutex() { m_mutex_count++; }