Kconfig: Migrate CONFIG_BAUDRATE

Move this in to Kconfig with a default of 115200.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
[trini: Run moveconfig.py, reword commit slightly]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/silk_defconfig b/configs/silk_defconfig
index 6be2945..eeba819 100644
--- a/configs/silk_defconfig
+++ b/configs/silk_defconfig
@@ -26,5 +26,6 @@
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_BAR=y
 CONFIG_SPI_FLASH_SPANSION=y
+CONFIG_BAUDRATE=38400
 CONFIG_USB=y
 CONFIG_USB_STORAGE=y