Convert CONFIG_CONSOLE_SCROLL_LINES to Kconfig

This converts the following to Kconfig:
   CONFIG_CONSOLE_SCROLL_LINES

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/chromebook_link_defconfig b/configs/chromebook_link_defconfig
index 86fc66b..d14cde5 100644
--- a/configs/chromebook_link_defconfig
+++ b/configs/chromebook_link_defconfig
@@ -62,5 +62,6 @@
 CONFIG_FRAMEBUFFER_VESA_MODE_11A=y
 CONFIG_VIDEO_IVYBRIDGE_IGD=y
 CONFIG_CFB_CONSOLE=y
+CONFIG_CONSOLE_SCROLL_LINES=5
 CONFIG_USE_PRIVATE_LIBGCC=y
 CONFIG_TPM=y