m68k: use strscpy() to instead of strncpy()

The implementation of strscpy() is more robust and safer.
Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

arch/m68k/kernel/setup_no.c

@@ -90,8 +90,7 @@ void __init setup_arch(char **cmdline_p)
 	config_BSP(&command_line[0], sizeof(command_line));
 
 #if defined(CONFIG_BOOTPARAM)
-	strncpy(&command_line[0], CONFIG_BOOTPARAM_STRING, sizeof(command_line));
-	command_line[sizeof(command_line) - 1] = 0;
+	strscpy(&command_line[0], CONFIG_BOOTPARAM_STRING, sizeof(command_line));
 #endif /* CONFIG_BOOTPARAM */
 
 	process_uboot_commandline(&command_line[0], sizeof(command_line));