FAT labels should be uppercase

...and both filesystem labels should be in the same case, for consistency

raspi3.yaml

@@ -22,11 +22,11 @@ steps:
 
   - mkfs: vfat
     partition: boot-part
-    label: raspiboot
+    label: RASPIFIRM
 
   - mkfs: ext4
     partition: root-part
-    label: raspiroot
+    label: RASPIROOT
 
   - mount: root-part
     fs-tag: root-fs
@@ -121,7 +121,7 @@ steps:
   # the partition labeled raspiroot instead of forcing it to mmcblk0p2
   - chroot: root-fs
     shell: |
-      sed -i 's/.dev.mmcblk0p2/LABEL=raspiroot/' /boot/firmware/cmdline.txt
+      sed -i 's/.dev.mmcblk0p2/LABEL=RASPIROOT/' /boot/firmware/cmdline.txt
 
   # TODO(https://github.com/larswirzenius/vmdb2/issues/24): remove once vmdb
   # clears /etc/resolv.conf on its own.