microblaze: Enable uart16550 DM by default

Microblaze is uses uartlite or uart16550 as console drivers.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/configs/microblaze-generic_defconfig b/configs/microblaze-generic_defconfig
index dc4ac05..0947c46 100644
--- a/configs/microblaze-generic_defconfig
+++ b/configs/microblaze-generic_defconfig
@@ -10,4 +10,5 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPL_OF_CONTROL=y
 CONFIG_OF_EMBED=y
+CONFIG_SYS_NS16550=y
 CONFIG_XILINX_UARTLITE=y