MIPS: Extend COMMAND_LINE_SIZE

Some firmware may pass well over 256 bytes these days.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/setup.h

 #ifndef _MIPS_SETUP_H
 #define _MIPS_SETUP_H
 
-#define COMMAND_LINE_SIZE	256
+#define COMMAND_LINE_SIZE	4096
 
 #ifdef  __KERNEL__
 extern void setup_early_printk(void);