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_jerry_defconfig b/configs/chromebook_jerry_defconfig
index e7e8b18..876adc4 100644
--- a/configs/chromebook_jerry_defconfig
+++ b/configs/chromebook_jerry_defconfig
@@ -76,6 +76,7 @@
 CONFIG_DM_VIDEO=y
 CONFIG_DISPLAY=y
 CONFIG_VIDEO_ROCKCHIP=y
+CONFIG_CONSOLE_SCROLL_LINES=10
 CONFIG_USE_TINY_PRINTF=y
 CONFIG_CMD_DHRYSTONE=y
 CONFIG_ERRNO_STR=y