[PATCH] fix generic_fls64()

Noticed by Rune Torgersen.

Fix generic_fls64().  tcp_cubic is using fls64().

Signed-off-by: Akinobu Mita <mita@miraclelinux.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>