mb/google/zork: Set USB3 port to force gen1 for morphius and ezkinil

In morphius, the USB3 typeA port needs to set to gen1, and for ezkinil
all the USB3 ports should force to gen1. So set the corresponding
setting to usb3_port_force_gen1 to force USB3 to Gen1.

BUG=b:167651308
BRANCH=zork
TEST=Build, verify the USB3 speed in gen1

Signed-off-by: Chris Wang <chris.wang@amd.corp-partner.google.com>
Change-Id: I10419b91fe86fe3e06de36ddfe0d1769c1031f8e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45334
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Sam McNally <sammc@google.com>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/mainboard/google/zork/variants/ezkinil/overridetree.cb

@@ -22,7 +22,12 @@ chip soc/amd/picasso
 
 	# End : OPN Performance Configuration
 
-	register "xhci0_force_gen1" = "1"
+	register "usb3_port_force_gen1" = "{
+		.ports.xhci0_port0 = 1,
+		.ports.xhci0_port1 = 1,
+		.ports.xhci0_port2 = 1,
+		.ports.xhci0_port3 = 1,
+	}"
 
 	# Enable I2C2 for trackpad, touchscreen, pen at 400kHz
 	register "i2c[2]" = "{

src/mainboard/google/zork/variants/morphius/overridetree.cb

@@ -30,6 +30,11 @@ chip soc/amd/picasso
 
 	# End : OPN Performance Configuration
 
+	register "usb3_port_force_gen1" = "{
+		.ports.xhci0_port1 = 1, /* Left USB3A port 1 */
+		.ports.xhci0_port2 = 1, /* Left USB3A port 2 */
+	}"
+
 	# Enable I2C2 for trackpad, touchscreen, pen at 400kHz
 	register "i2c[2]" = "{
 		.speed = I2C_SPEED_FAST,