Convert CONFIG_SYS_TIMER_COUNTS_DOWN to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_TIMER_COUNTS_DOWN

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/r2dplus_defconfig b/configs/r2dplus_defconfig
index cee9a1f..4217175 100644
--- a/configs/r2dplus_defconfig
+++ b/configs/r2dplus_defconfig
@@ -57,4 +57,5 @@
 CONFIG_DM_SERIAL=y
 CONFIG_SERIAL_RX_BUFFER=y
 CONFIG_SCIF_CONSOLE=y
+CONFIG_SYS_TIMER_COUNTS_DOWN=y
 CONFIG_USE_PRIVATE_LIBGCC=y