kernel-doc: code reorganization

Move 'main' code vs. subroutines around so that they are not so
intermixed, for better readability/understanding (relative to Perl).
It was messy to follow the primary flow of code execution with the
code being mixed.  Now the code begins with data initialization,
followed by all subroutines, then ends with the main code execution.

This is almost totally source code movement, with a few changes as
needed for forward declarations.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>