Staging: batman-adv: cleanup: change test for end of array

Staging: batman-adv: cleanup: change test for end of array

The code here is testing to see if "i" is passed the end of the array.
The original code works probably, but it's not the cleanest way.

Andrew Lunn suggested that I also remove all the hard coded references
to 256 so I have done that as well.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>