The recently introduced wide pipeline for filters has a typo which
causes it to improperly compute bilinear interpolation positions,
causing various glitches when enabled.

This patch uses the proper computation for bilinear interpolation in the
wide pipeline.  It also makes related `if` statements conformant to the
CODING_STYLE:

* If a substatement spans multiple lines, then there must be braces
  around it.

* If one substatement of an if statement has braces, then the other
  must too.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>