fscrypt: make test_dummy_encryption use v2 by default

Since v1 encryption policies are deprecated, make test_dummy_encryption
test v2 policies by default.

Note that this causes ext4/023 and ext4/028 to start failing due to
known bugs in those tests (see previous commit).

Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Jaegeuk Kim <[email protected]>
Reviewed-by: Theodore Ts'o <[email protected]>
Signed-off-by: Eric Biggers <[email protected]>

Author: ebiggers

fs/crypto/policy.c

@@ -643,7 +643,7 @@ int fscrypt_set_test_dummy_encryption(struct super_block *sb,
 				      const substring_t *arg,
 				      struct fscrypt_dummy_context *dummy_ctx)
 {
-	const char *argstr = "v1";
+	const char *argstr = "v2";
 	const char *argstr_to_free = NULL;
 	struct fscrypt_key_specifier key_spec = { 0 };
 	int version;