libata: Convert bare printks to pr_cont

Linus Torvalds changed the behavior of printks without KERN_<LEVEL>.

Convert the continuation prints to use pr_cont.

At the same time, convert the existing printks with KERN_<LEVEL> to
pr_<level>

Miscellanea:

o Coalesce a multiline format

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Tejun Heo <tj@kernel.org>