Remove double rounding in selfguided filter
Remove double rounding in selfguided filter

In av1_selfguided_restoration, the values stored into 'dgd' are
unnecessarily rounded twice. This patch replaces this by a single
rounding operation.

Change-Id: I188d283137b74823f5d5447d441250520d6ee294

GrokImageCompression/aom,smarter/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,smarter/aom,smarter/aom,GrokImageCompression/aom,GrokImageCompression/aom,luctrudeau/aom,smarter/aom,luctrudeau/aom,luctrudeau/aom,GrokImageCompression/aom