checkpatch: printks always need a KERN_<LEVEL>

There was code in checkpatch that allowed continuation printks to be
used without KERN_CONT.  Remove the continuation check and always
require a KERN_<LEVEL>.

Link: http://lkml.kernel.org/r/61980ef41d5b9b6543da1c49055042e0ab74d308.1507047008.git.joe@perches.com


Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>