kernel-yocto: Fix case where recipe is always reparsed
If you include a bitbake variable as a comment in a shell function
then it gets expanded by the bitbake signature handling code.
This could be classed as a bug or a feature depending on your viewpoint
(e.g. a multiline variable included in a comment could actually contain
executable code).
Since we don't always want kernel-yocto to reparse this changes the
syntax of the comment so it doesn't trigger the problem.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
