soc/amd/picasso: introduce and use devicetree aliases for UART0-3

Since the default state of the MMIO UART devices in the chipset
devicetree is off, the mainboard devicetree entries that disable MMIO
UART devices are removed.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I913a587802020ce4e182b48632cdde1104c2a6e6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55545
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/google/zork/variants/baseboard/devicetree_dalboz.cb b/src/mainboard/google/zork/variants/baseboard/devicetree_dalboz.cb
index f17eca7..0cf969c 100644
--- a/src/mainboard/google/zork/variants/baseboard/devicetree_dalboz.cb
+++ b/src/mainboard/google/zork/variants/baseboard/devicetree_dalboz.cb
@@ -395,9 +395,6 @@
 		end
 	end
 
-	device mmio 0xfedc9000 on end # console on UART0
-	device mmio 0xfedca000 off end # UART1
-	device mmio 0xfedce000 off end # UART2
-	device mmio 0xfedcf000 off end # UART3
+	device ref uart_0 on end # console
 
 end	# chip soc/amd/picasso