config: Enable Raspberry Pi 3B+ in my lab

Basic enablement for core features of the board which I've added to my
lab.

Signed-off-by: Mark Brown <broonie@kernel.org>

Author: broonie

config/platforms.yaml

@@ -32,6 +32,12 @@ platforms:
     dtb: dtbs/broadcom/bcm2711-rpi-4-b.dtb
     compatible: ['raspberrypi,4-model-b', 'brcm,bcm2711']
 
+  bcm2837-rpi-3-b-plus:
+    <<: *arm64-device
+    mach: broadcom
+    dtb: dtbs/broadcom/bcm2837-rpi-3-b-plus.dtb
+    compatible: ['raspberrypi,3-model-b-plus', rbrcm,bcm2837;]
+
   # No job is being scheduled on these board as its infrastructure errors need to be fixed first.
   bcm2836-rpi-2-b:
     <<: *arm-device

config/scheduler.yaml

@@ -116,6 +116,7 @@ scheduler:
       name: lava-broonie
     platforms: &lava-broonie-arm64
       - bcm2711-rpi-4-b
+      - bcm2837-rpi-3-b-plus
       - imx8mp-evk
       - imx8mp-verdin-nonwifi-dahlia
       - juno
@@ -662,6 +663,7 @@ scheduler:
     runtime: *lava-broonie-runtime
     platforms:
       - bcm2711-rpi-4-b
+      - bcm2837-rpi-3-b-plus
       - imx8mp-evk
       - imx8mp-verdin-nonwifi-dahlia
       - meson-g12b-a311d-libretech-cc