libpcp_web: correct the json bytes offset/pointer calculation
libpcp_web: correct the json bytes offset/pointer calculation

Ensure the correct buffer offset is used when copying data.

adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp,adfernandes/pcp