ext4l: Add stubs for xattr functions used by ialloc.c

Add stub declarations and implementations for xattr functions that
ialloc.c calls but which are defined in xattr.c (not yet compiled):
- __ext4_xattr_set_credits
- ext4_init_security

Add declarations to ext4_uboot.h and implementations to stub.c.

Co-developed-by: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>

fs/ext4l/ext4_uboot.h

@@ -366,9 +366,15 @@ extern struct user_namespace init_user_ns;
 #ifndef _FS_EXT4_ACL_H
 #define ext4_init_acl(h, i, d)			({ (void)(h); (void)(i); (void)(d); 0; })
 #endif
-/* Note: ext4_init_security is already handled in xattr.h */
+/* xattr stubs for files that don't include xattr.h */
+struct super_block;
+struct buffer_head;
+struct qstr;
 
-/* xattr stubs - __ext4_xattr_set_credits is declared in xattr.h */
+int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
+			     struct buffer_head *block_bh, size_t value_len,
+			     bool is_create);
+/* ext4_init_security is declared in xattr.h */
 
 /* inode state stubs */
 #define is_bad_inode(inode)			(0)

fs/ext4l/stub.c

@@ -377,3 +377,21 @@ struct buffer_head *ext4_sb_bread_nofail(struct super_block *sb,
 {
 	return NULL;
 }
+
+/*
+ * Stubs for ialloc.c - xattr functions
+ */
+int __ext4_xattr_set_credits(struct super_block *sb, struct inode *inode,
+			     struct buffer_head *block_bh, size_t value_len,
+			     bool is_create)
+{
+	return 0;
+}
+
+struct qstr;
+
+int ext4_init_security(void *handle, struct inode *inode, struct inode *dir,
+		       const struct qstr *qstr)
+{
+	return 0;
+}