Remove copy_border from loop restoration filters

This function corrected for the fact that the old bilateral and
Wiener filters would not write to the outermost 3 pixels of the
destination. Now that the bilateral filter has been removed and
the Wiener filter has been rewritten, this is no longer necessary.

No effect on performance

Change-Id: I3f3b0a759bdb9ff1e2407affe963388e76a9c9e6