tegra-flash-helper: Allow PKC-only secure boot flashing

When flashing a board fused with PKC hash but no SBK, we should not
supply a SBK key as that would encrypt the flash contents which would
then not be able to be read by the board when booting, as the board
won't know the SBK key.

Signed-off-by: Andrew Bradford <andrew.bradford@konsulko.com>

recipes-bsp/tegra-binaries/tegra-helper-scripts/tegra-flash-helper.sh

@@ -259,7 +259,13 @@ if [ -z "$CHIPREV" ]; then
     CHIPREV="${chipid:5:1}"
     skipuid="--skipuid"
     case $bootauth in
-        PKC|SBKPKC)
+        PKC)
+            if [ -z "$keyfile" ]; then
+                echo "ERR: Target is configured for secure boot ($bootauth); use -u option to specify key file" >&2
+                exit 1
+            fi
+            ;;
+        SBKPKC)
             if [ -z "$keyfile" -o -z "$sbk_keyfile" ]; then
                 echo "ERR: Target is configured for secure boot ($bootauth); use -u and -v options to specify key files" >&2
                 exit 1