.github: add rpi2 bootloader and SD card image builds

Add Raspberry Pi 2B to the bootloader build matrix and raspberrypi-rpi2
to the SD card image builder, enabling full RPi 2B image creation.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/build-boot.yml

@@ -22,6 +22,7 @@ jobs:
           - cn9130_crb_boot
           - fireant_boot
           - nanopi_r2s_boot
+          - rpi2_boot
           - rpi64_boot
     env:
       MAKEFLAGS: -j5

.github/workflows/build-image.yml

@@ -8,6 +8,7 @@ on:
         type: choice
         required: true
         options:
+          - raspberrypi-rpi2
           - raspberrypi-rpi64
           - bananapi-bpi-r3
           - friendlyarm-nanopi-r2s
@@ -49,6 +50,11 @@ jobs:
       - name: Set bootloader and target based on board
         run: |
           case "${{ inputs.board }}" in
+            raspberrypi-rpi2)
+              echo "BOOTLOADER=rpi2-boot" >> $GITHUB_ENV
+              echo "ARCH=arm" >> $GITHUB_ENV
+              echo "BUILD_EMMC=false" >> $GITHUB_ENV
+              ;;
             raspberrypi-rpi64)
               echo "BOOTLOADER=rpi64-boot" >> $GITHUB_ENV
               echo "ARCH=aarch64" >> $GITHUB_ENV