Fix AFFS with non-512B blocks.

	Fix AFFS with non-512B blocks.

	* grub-core/fs/affs.c (grub_affs_rblock): Make type uint32_t.
	(AFFS_MAX_LOG_BLOCK_SIZE): New definition.
	(grub_affs_data): Replace blocksize with log_blocksize.
	(grub_affs_read_block): Fix non-512B blocks.
	(grub_affs_read_symlink): Likewise.
	(grub_affs_iterate_dir): Likewise. Fix freeing corruption.
	(grub_affs_read): Fix non-512B blocks.
	(grub_affs_label): Likewise.
	(grub_affs_mtime): Likewise.
	(grub_affs_mount): Fix block detection routine.