serial: uartlite: Add uartlite to Kconfig

- Move config option out of board file.
- Remove uartlite address from config file

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Thomas Chou <thomas@wytron.com.tw>
diff --git a/configs/microblaze-generic_defconfig b/configs/microblaze-generic_defconfig
index 6b038b8..dc4ac05 100644
--- a/configs/microblaze-generic_defconfig
+++ b/configs/microblaze-generic_defconfig
@@ -10,3 +10,4 @@
 # CONFIG_CMD_SETEXPR is not set
 CONFIG_SPL_OF_CONTROL=y
 CONFIG_OF_EMBED=y
+CONFIG_XILINX_UARTLITE=y