soc/intel/broadwell: Re-do SerialIO UART console support

Use the same code from Lynx Point on Broadwell, and adjust as needed.
Also add a config file to ensure the code gets build-tested.

Tested on out-of-tree Compal LA-A992P (Haswell ULT), UART 0 works.

Change-Id: I527024098738700d5fbaf3e27cf4db331a0322bd
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37553
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

configs/config.google_guado.pch_serialio_uart

@@ -0,0 +1,5 @@
+# Configuration used to build-test Wildcat Point SerialIO UART console code.
+CONFIG_VENDOR_GOOGLE=y
+CONFIG_BOARD_GOOGLE_GUADO=y
+CONFIG_SERIALIO_UART_CONSOLE=y
+# CONFIG_DRIVERS_UART_8250IO is not set