revert a small change from Ton's commit from r33637.

Having edit operations select the mirrored bones means you cant so easily continue editing on one side of the armature.
This is also inconsistent with other mirror editing operations in armature and mesh modes which don't adjust selection like this.

source/blender/editors/armature/editarmature.c

@@ -3730,9 +3730,6 @@ static int armature_switch_direction_exec(bContext *C, wmOperator *UNUSED(op))
 	chains_find_tips(arm->edbo, &chains);
 	if (chains.first == NULL) return OPERATOR_CANCELLED;
 	
-	/* leaves mirrored bones selected, as indication of operation */
-	armature_select_mirrored(arm);
-	
 	/* loop over chains, only considering selected and visible bones */
 	for (chain= chains.first; chain; chain= chain->next) {
 		EditBone *ebo, *child=NULL, *parent=NULL;