!10670 fix maskrcnn 16p performance bug

From: @gengdongjie
Reviewed-by: @oacjiewen,@linqingke
Signed-off-by: @linqingke

model_zoo/official/cv/maskrcnn/scripts/run_distribute_train.sh

@@ -54,7 +54,7 @@ export RANK_TABLE_FILE=$PATH1
 echo 3 > /proc/sys/vm/drop_caches
 
 cpus=`cat /proc/cpuinfo| grep "processor"| wc -l`
-avg=`expr $cpus \/ $RANK_SIZE`
+avg=`expr $cpus \/ $DEVICE_NUM`
 gap=`expr $avg \- 1`
 
 for((i=0; i<${DEVICE_NUM}; i++))