This patch updates the filter the way it could handle all possible ampersand
notations. It effectively replaces patch 858f1b9a

 with more approprate
approach suggested by Richard.

Change-Id: I084fb04b5d1cad22006e390509ea610e2aec3e78
Signed-off-by: Richard Mansfield <richard.mansfield@catalyst.net.nz>
Signed-off-by: Ruslan Kabalin <ruslan.kabalin@luns.net.uk>