checkpatch: fix defect in printk(KERN_<LEVEL> 80 column exceptions

Currently, printk lines with a only KERN_PREFIX and a quoted string
without a comma or close paren that exceed 80 columns are flagged with a
warning.

ie:
	printk(KERN_WARNING "some long string that extends beond 80 cols..."
	       "and is continued on another line\n");

Allow this form instead of emitting a warning.

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