Convert CONSOLE_PRE_CONSOLE_BUFFER options to Kconfig

Move these option to Kconfig and tidy up existing uses.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagan Teki <jteki@openedev.com>
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index b139d1c..c0ffeb3 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -3,6 +3,9 @@
 config IDENT_STRING
 	default " Allwinner Technology"
 
+config PRE_CONSOLE_BUFFER
+	default y
+
 config SPL_GPIO_SUPPORT
 	default y