Fix rpi-eeprom-update when device boots from NVMe (#4205)

* Fix rpi-eeprom-update when device boots from NVMe

The boot partition detection doesn't work correctly if the device boots from
NVMe. Also the mounting step is unnecessary in HAOS as we can assume the boot
partition to be always mounted.

Fix the issues by modifying the bootfs detection logic to always use /mnt/boot.
However, still fail in case when flashrom can't be used (usually on CM4). On
CM5, or on Pi 5 booted from NVMe, update process works without further changes
because the firmware can be flashed directly from the running system using
flashrom.

Fixes #4157

* Fix typo in patch commit message

Author: sairon

buildroot-external/package/rpi-eeprom/0001-rpi-eeprom-update-adjust-bootfs-discovery-for-HAOS.patch

@@ -0,0 +1,53 @@
+From 5b3c41b3465a98025b6869c4ed14d210b68b7e24 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Jan=20=C4=8Cerm=C3=A1k?= <[email protected]>
+Date: Tue, 13 May 2025 17:19:59 +0200
+Subject: [PATCH] rpi-eeprom-update: adjust bootfs discovery for HAOS
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+When HAOS boots from SD card, we can rely on /mnt/boot being mounted and
+use it for storing the recovery image. If it's not on an SD card, we can
+only use it to store the image if flashrom is used, otherwise the
+bootloader doesn't pick it up - in that case show an error (e.g. on CM4
+booting from an NVMe).
+
+Signed-off-by: Jan Čermák <[email protected]>
+Upstream: not applicable
+---
+ rpi-eeprom-update | 22 ++++++++--------------
+ 1 file changed, 8 insertions(+), 14 deletions(-)
+
+diff --git a/rpi-eeprom-update b/rpi-eeprom-update
+index b970142..3e9d75f 100755
+--- a/rpi-eeprom-update
++++ b/rpi-eeprom-update
+@@ -725,20 +725,14 @@ findBootFS()
+    # If ${BOOTFS} is not writable OR is not on /dev/mmcblk0 then error because the ROM
+    # can only load recovery.bin from the on-board SD-CARD slot or the EEPROM.
+ 
+-   if blkid | grep -qE "/dev/mmcblk0p1.*LABEL_FATBOOT.*RECOVERY.*TYPE.*vfat"; then
+-      TMP_BOOTFS_MNT="$(mktemp -d)"
+-      mount /dev/mmcblk0p1 "${TMP_BOOTFS_MNT}"
+-      BOOTFS="${TMP_BOOTFS_MNT}"
+-   elif [ -z "$BOOTFS" ]; then
+-      if ! BOOTFS=$(/usr/lib/raspberrypi-sys-mods/get_fw_loc 2> /dev/null); then
+-         for BOOTFS in /boot/firmware /boot; do
+-            if [ -f "${BOOTFS}/config.txt" ]; then
+-               break
+-            elif findmnt --fstab "$BOOTFS" > /dev/null; then
+-               break
+-            fi
+-         done
+-      fi
++   if blkid | grep -qE "/dev/mmcblk0p1.*LABEL_FATBOOT.*hassos-boot.*TYPE.*vfat"; then
++      # use HAOS default bootfs location if booting from SD card
++      BOOTFS="/mnt/boot"
++   elif [ -z "$BOOTFS" ] && [ "${RPI_EEPROM_USE_FLASHROM}" = "1" ]; then
++      # image for flashrom will created in bootfs
++      BOOTFS="/mnt/boot"
++   elif [ -z "$BOOTFS" ]; then
++      die "rpi-eeprom-update is only available when booting from an SD card or if flashrom can be used."
+    fi
+ 
+    # If BOOTFS is not a directory or doesn't contain any .elf files then