logging: remove unescessary init

kernel-src/arch/x86-64/main.c

@@ -45,7 +45,6 @@ static cpu_t bsp_cpu;
 
 void kernel_entry() {
 	cpu_set(&bsp_cpu);
-	logging_init();
 	logging_sethook(arch_e9_putc);
 
 	arch_gdt_reload();

kernel-src/io/logging.c

@@ -1,6 +1,6 @@
 #include <mutex.h>
 
-mutex_t printf_mutex;
+MUTEX_DEFINE(printf_mutex);
 
 static void nohook(char c) {
 
@@ -16,7 +16,3 @@ void _putchar(char c) {
 void logging_sethook(void (*fun)(char)) {
 	hook = fun;
 }
-
-void logging_init() {
-	MUTEX_INIT(&printf_mutex);
-}