Use CONFIG_VAL(DEBUG_UART_BASE) instead of CONFIG_DEBUG_UART_BASE, so
proper config value (CONFIG_DEBUG_UART_BASE or CONFIG_SPL_DEBUG_UART_BASE)
is used based on building target.
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>