Kernel: Move smp_initialized flag after schedulers are initialized

Before this real hardware failed to boot with smp enabled. Allocating
the idle thread does a page mapping which ends up broadcasting TLB
shootdown to other processes. This ends up failing somewhere halting the
processors never allowing them to initialize their scheduler

kernel/include/kernel/Processor.h

@@ -57,8 +57,9 @@ namespace Kernel
 		static ProcessorID current_id() { return read_gs_sized<ProcessorID>(offsetof(Processor, m_id)); }
 		static ProcessorID id_from_index(size_t index);
 
-		static uint8_t count()       { return s_processor_count; }
-		static bool is_smp_enabled() { return s_is_smp_enabled; }
+		static uint8_t count()        { return s_processor_count; }
+		static bool is_smp_enabled()  { return s_is_smp_enabled; }
+		static void set_smp_enabled() { s_is_smp_enabled = true; }
 		static void wait_until_processors_ready();
 
 		static void toggle_should_print_cpu_load() { s_should_print_cpu_load = !s_should_print_cpu_load; }

kernel/kernel/Processor.cpp

@@ -189,8 +189,6 @@ namespace Kernel
 				__builtin_ia32_pause();
 			}
 		}
-
-		s_is_smp_enabled = true;
 	}
 
 	void Processor::handle_ipi()

kernel/kernel/Scheduler.cpp

@@ -136,6 +136,9 @@ namespace Kernel
 		while (s_schedulers_initialized < Processor::count())
 			__builtin_ia32_pause();
 
+		if (Processor::count() > 1)
+			Processor::set_smp_enabled();
+
 		return {};
 	}