f2fs: add support for IV_INO_LBLK_64 encryption policies

f2fs inode numbers are stable across filesystem resizing, and f2fs inode
and file logical block numbers are always 32-bit.  So f2fs can always
support IV_INO_LBLK_64 encryption policies.  Wire up the needed
fscrypt_operations to declare support.

Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>