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/harmony_defconfig b/configs/harmony_defconfig
index e1691f6..5c76af3 100644
--- a/configs/harmony_defconfig
+++ b/configs/harmony_defconfig
@@ -41,3 +41,4 @@
 CONFIG_USB_STORAGE=y
 CONFIG_DM_VIDEO=y
 CONFIG_VIDEO_TEGRA20=y
+CONFIG_CONSOLE_SCROLL_LINES=10