rockchip: Turn off CONFIG_SPL_LED for firefly

With LED support enabled the SPL easily goes over the size limit (e.g.
with both Debians gcc 4.9 and 5.2 cross-compilers). Turn off LED support
in the SPL to reduce the size just enough for those compilers.
Signed-off-by: NSjoerd Simons <sjoerd.simons@collabora.co.uk>
Tweaked commit subject to remove _SUPPORT
Signed-off-by: NSimon Glass <sjg@chromium.org>

configs/firefly-rk3288_defconfig

@@ -17,7 +17,6 @@ CONFIG_REGMAP=y
 CONFIG_SYSCON=y
 CONFIG_RESET=y
 CONFIG_LED=y
-CONFIG_SPL_LED=y
 CONFIG_LED_GPIO=y
 CONFIG_DEBUG_UART=y
 CONFIG_DEBUG_UART_BASE=0xff690000