checkpatch: fix continuation detection when handling spacing on operators

We are miscategorising a continuation fragment following an operator
which may lead to us thinking that there is a space after it when there is
not.  Fix this up.

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