f2fs: Restrict max filesize for 16K f2fs

Blocks are tracked by u32, so the max permitted filesize is
(U32_MAX + 1) * BLOCK_SIZE. Additionally, in order to support crypto
data unit sizes of 4K with a 16K block with IV_INO_LBLK_{32,64}, we must
further restrict max filesize to (U32_MAX + 1) * 4096. This does not
affect 4K blocksize f2fs as the natural limit for files are well below
that.

Fixes: d7e9a903 ("f2fs: Support Block Size == Page Size")
Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>