soc/amd/common/psp_verstage: Write postcodes after ESPI init

On boards where PSP uses ESPI to write postcodes, update the verstage to
do it after ESPI initialization.

BUG=b:224543620
TEST=Build and boot to OS in Nipperkin. Ensure that there are no
attempts to write the post code from PSP verstage before ESPI
initialization.

Change-Id: I1b78931c741c75dc845c9b34e3b2b896221f2364
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62880
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mohan Viswanathan
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/soc/amd/cezanne/Kconfig

@@ -345,6 +345,14 @@ config PSP_DISABLE_POSTCODES
 	help
 	  Disables the output of port80 post codes from PSP.
 
+config PSP_POSTCODES_ON_ESPI
+	bool "Use eSPI bus for PSP post codes"
+	depends on !PSP_DISABLE_POSTCODES
+	default y
+	help
+	  Select to send PSP port80 post codes on eSPI bus.
+	  If not selected, PSP port80 codes will be sent on LPC bus.
+
 config PSP_INIT_ESPI
 	bool "Initialize eSPI in PSP Stage 2 Boot Loader"
 	help