soc/amd/picasso: Set VERSTAGE_ADDR for picasso

By default ROMSTAGE_ADDR and VERSTAGE_ADDR are set to 0x2000000. This
causes problems in a non-xip environment because when verstage loads
romstage, it overrides it's memory. So pick a different offset for
verstage.

BUG=b:147042464
TEST=Boot verstage on trembyle and see OS boot.

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I2464db6f3769bd23d250588b341d1c9e44f10d21
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41367
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/amd/picasso/Kconfig

@@ -81,6 +81,10 @@ config MMCONF_BUS_NUMBER
 	int
 	default 64
 
+config VERSTAGE_ADDR
+	hex
+	default 0x4000000
+
 config VGA_BIOS_ID
 	string
 	default "1002,15d8"