This got lost when we shuffled around our internal branch and
GEN7_FEATURES macro. There were no HW changes to support FBC, so we just
need to set the flag.
v2: Don't allow FBC for any pipe but A on platforms with DDI. (Paulo)
Cc: Daisy Sun <daisy.sun@intel.com> Signed-off-by: Ben Widawsky <ben@bwidawsk.net> Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>