Fix docker storage path while calculating disk usage from within the container.
Fix docker storage path while calculating disk usage from within the container.

Signed-off-by: Vishnu kannan <8c9a7175bd62235d51889a4697184181a7bcfb30@google.com>

datawisesystems/cadvisor,f0/cadvisor,ainsleyc/cadvisor,erSitzt/cadvisor,BrickXu/cadvisor,BrickXu/cadvisor,jhjeong-kr/cadvisor,ncdc/cadvisor,f0/cadvisor,BrickXu/cadvisor,dchen1107/cadvisor,erSitzt/cadvisor,dchen1107/cadvisor,linux-on-ibm-z/cadvisor,IFTTT/cadvisor,erSitzt/cadvisor,jhjeong-kr/cadvisor,erSitzt/cadvisor,timstclair/cadvisor,linux-on-ibm-z/cadvisor,ncdc/cadvisor,ainsleyc/cadvisor,linux-on-ibm-z/cadvisor,dchen1107/cadvisor,ncdc/cadvisor,f0/cadvisor,f0/cadvisor,dchen1107/cadvisor,derekwaynecarr/cadvisor,IFTTT/cadvisor,derekwaynecarr/cadvisor,jhjeong-kr/cadvisor,IFTTT/cadvisor,guoshimin/cadvisor,datawisesystems/cadvisor,ncdc/cadvisor,jhjeong-kr/cadvisor,derekwaynecarr/cadvisor,ainsleyc/cadvisor,guoshimin/cadvisor,dchen1107/cadvisor,IFTTT/cadvisor,timstclair/cadvisor,shilpamayanna/cadvisor,ainsleyc/cadvisor,BrickXu/cadvisor,derekwaynecarr/cadvisor,ncdc/cadvisor,guoshimin/cadvisor,shilpamayanna/cadvisor,derekwaynecarr/cadvisor,timstclair/cadvisor,erSitzt/cadvisor,jhjeong-kr/cadvisor,BrickXu/cadvisor,f0/cadvisor,IFTTT/cadvisor