axm/taurus: Enable tiny printf in SPL

Both of these boards are very close to their limit and with some toolchains
such as gcc 5.x are too large.  Switch to tiny printf to reclaim some size.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/taurus_defconfig b/configs/taurus_defconfig
index d59912c..3f08cc1 100644
--- a/configs/taurus_defconfig
+++ b/configs/taurus_defconfig
@@ -13,3 +13,4 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_USE_TINY_PRINTF=y