checkpatch: improve Kconfig help test

checkpatch: improve Kconfig help test

The Kconfig help test erroneously counts patch context lines as part of
the help text.

Fix that and improve the message block output.

Link: https://lkml.kernel.org/r/06c0cdc157ae1502e8e9eb3624b9ea995cf11e7a.camel@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>