tree-wide: s/struct fileattr/struct file_kattr/g

Now that we expose struct file_attr as our uapi struct rename all the
internal struct to struct file_kattr to clearly communicate that it is a
kernel internal struct. This is similar to struct mount_{k}attr and
others.

Link: https://lore.kernel.org/20250703-restlaufzeit-baurecht-9ed44552b481@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>

security/selinux/hooks.c

@@ -3481,13 +3481,13 @@ static int selinux_inode_removexattr(struct mnt_idmap *idmap,
 }
 
 static int selinux_inode_file_setattr(struct dentry *dentry,
-				      struct fileattr *fa)
+				      struct file_kattr *fa)
 {
 	return dentry_has_perm(current_cred(), dentry, FILE__SETATTR);
 }
 
 static int selinux_inode_file_getattr(struct dentry *dentry,
-				      struct fileattr *fa)
+				      struct file_kattr *fa)
 {
 	return dentry_has_perm(current_cred(), dentry, FILE__GETATTR);
 }