mb/google/rex: Add USB4 ANX7452 Rev 2 to USB_DB FW_CONFIG

This patch adds new USB_DB FW_CONFIG to enable support for USB4 ANX7452
Rev 2.

BUG=b:279647370
TEST=Able to build and boot google/rex with Proto 2 SKU

Signed-off-by: Subrata Banik <subratabanik@google.com>
Change-Id: I878b591e5919d05d3c5fc2eefdeb492e95d4f7b5
Reviewed-on: https://review.coreboot.org/c/coreboot/+/74775
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: YH Lin <yueherngl@google.com>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>
Reviewed-by: Kapil Porwal <kapilporwal@google.com>

src/mainboard/google/rex/variants/rex0/overridetree.cb

@@ -27,6 +27,7 @@ fw_config
 		option USB4_KB8010		2
 		option USB4_ANX7452		3
 		option USB4_HAYDEN_BRIDGE	4
+		option USB4_ANX7452_V2		5
 	end
 	field FP 15
 		option FP_PRESENT		0