Staging: epl: fix up epl/kernel/*.h files

Only include a file if it's needed.

Also remove some unused comments from the boilerplate text.

And delete some empty .h files

Cc: Daniel Krueger <daniel.krueger@systec-electronic.com>
Cc: Ronald Sieber <Ronald.Sieber@systec-electronic.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>