mb/google/volteer/var/elemi: use devtree aliases for PMC MUX connectors

refer to cb:45878
Now that soc_get_pmc_mux_device() is gone, the PMC MUX connector devices
can be hooked up together via devicetree aliases.

BUG=b:174735512
BRANCH=volteer
TEST=build and type-c display work

Change-Id: I0bf84e2691856c9760d8fa9b6d853b04be10390a
Signed-off-by: Wisley Chen <wisley.chen@quantatw.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/48268
Reviewed-by: YH Lin <yueherngl@google.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/google/volteer/variants/elemi/overridetree.cb

@@ -183,6 +183,13 @@ chip soc/intel/tigerlake
 				device i2c 15 on end
 			end
 		end
+		device ref pch_espi on
+			chip ec/google/chromeec
+				use conn0 as mux_conn[0]
+				use conn1 as mux_conn[1]
+				device pnp 0c09.0 on end
+			end
+		end
 		device ref hda on
 			chip drivers/generic/max98357a
 				register "hid" = ""MX98357A""
@@ -201,14 +208,14 @@ chip soc/intel/tigerlake
 						register "usb2_port_number" = "9"
 						register "usb3_port_number" = "1"
 						# SBU & HSL follow CC
-						device generic 0 on end
+						device generic 0 alias conn0 on end
 					end
 					chip drivers/intel/pmc_mux/conn
 						register "usb2_port_number" = "4"
 						register "usb3_port_number" = "2"
 						# SBU is fixed, HSL follows CC
 						register "sbu_orientation" = "TYPEC_ORIENTATION_NORMAL"
-						device generic 1 on end
+						device generic 1 alias conn1 on end
 					end
 				end
 			end