Optional luks2Hash with enum

src/modules/luksbootkeyfile/luksbootkeyfile.conf

@@ -5,6 +5,9 @@
 # LUKS encrypted devices.
 ---
 # Set Password-Based Key Derivation Function (PBKDF) algorithm
-# for LUKS keyslot. The PBKDF can be: pbkdf2, argon2i or argon2id.
-# Default: pbkdf2
-luks2Hash: pbkdf2
+# for LUKS keyslot.
+#
+# There are three usable values: pbkdf2, argon2i or argon2id.
+#
+# When not set, the cryptsetup default is used
+#luks2Hash: argon2id

src/modules/luksbootkeyfile/luksbootkeyfile.schema.yaml

@@ -6,4 +6,4 @@ $id: https://calamares.io/schemas/luksbootkeyfile
 additionalProperties: false
 type: object
 properties:
-    luks2Hash: { type: string }
+    luks2Hash: { type: string, enum: [ pbkdf2, argon2i, argon2id ] }