Do not mention casts for u64/s64.  Complements commit 2a7930bd
("Documentation/printk-formats.txt: No casts needed for u64/s64").
Signed-off-by: NIlya Dryomov <ilya.dryomov@inktank.com>
Acked-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>