nios2: remove custom early console implementation

As of commits d8f347ba35cf ("nios2: enable earlycon support"),
0dcc0542a0 ("serial: altera_jtaguart: add earlycon support") and
4d9d7d896d ("serial: altera_uart: add earlycon support"), the nios2
architecture and the altera_uart/altera_jtaguart drivers support
earlycon. Thus, the custom early console implementation for nios2 is no
longer necessary to get early boot messages. Remove it and rely fully on
earlycon support.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

arch/nios2/kernel/setup.c

@@ -147,10 +147,6 @@ void __init setup_arch(char **cmdline_p)
 
 	console_verbose();
 
-#ifdef CONFIG_EARLY_PRINTK
-	setup_early_printk();
-#endif
-
 	memory_start = PAGE_ALIGN((unsigned long)__pa(_end));
 	memory_end = (unsigned long) CONFIG_NIOS2_MEM_BASE + memory_size;