mb/google/myst: Enable console UART

Enable the console UART for myst devices.

Bug=b:275900837
TEST=builds

Signed-off-by: Jon Murphy <jpmurphy@google.com>
Change-Id: I52c1b86c46907216d88f98917968b833af0d5d41
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74103
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Tim Van Patten <timvp@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>

src/mainboard/google/myst/Kconfig

@@ -7,6 +7,7 @@ if BOARD_GOOGLE_BASEBOARD_MYST
 
 config BOARD_SPECIFIC_OPTIONS
 	def_bool y
+	select AMD_SOC_CONSOLE_UART
 	select BOARD_ROMSIZE_KB_16384
 	select EC_GOOGLE_CHROMEEC
 	select EC_GOOGLE_CHROMEEC_ESPI

src/mainboard/google/myst/variants/baseboard/devicetree.cb

@@ -7,4 +7,5 @@ chip soc/amd/phoenix
 			end
 		end
 	end # domain
+	device ref uart_0 on end # UART0
 end	# chip soc/amd/phoenix