staging: bcm: fix error do not use c99 comments

This patch fixes checkpatch.pl error in InterfaceMacros.h file
ERROR: do not use C99 // comments

Signed-off-by: Tapasweni Pathak <tapaswenipathak@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>