checkpatch: statement/block context analyser should look at sanitised lines

When tracking context to find a block or statement we need to use the
sanitised lines, else perentheses '(' & ')' and braces '{' & '}' can throw
the scanner out.  Also fix up a couple of error outputs which include
those sanitised lines incorrectly.

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>