Staging: winbond: Fix C99 Comment issues in mac_structures.h

This patch fixes the use of //C99 comments in the mac_structures.h found by
the checkpatch.pl tool

Signed-off-by: Adam Latham <adam.latham@unisontorbay.org.uk>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>