Drop the log buffer

This does not appear to be used by any boards. Before introducing a new
log system, remove this old one.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

common/stdio.c

@@ -17,9 +17,6 @@
 #include <malloc.h>
 #include <stdio_dev.h>
 #include <serial.h>
-#ifdef CONFIG_LOGBUFFER
-#include <logbuff.h>
-#endif
 
 #if defined(CONFIG_SYS_I2C)
 #include <i2c.h>
@@ -380,9 +377,6 @@ int stdio_add_devices(void)
 #endif /* CONFIG_DM_VIDEO */
 #if defined(CONFIG_KEYBOARD) && !defined(CONFIG_DM_KEYBOARD)
 	drv_keyboard_init ();
-#endif
-#ifdef CONFIG_LOGBUFFER
-	drv_logbuff_init ();
 #endif
 	drv_system_init ();
 	serial_stdio_init ();