rmse was wrongly calculated
rmse was wrongly calculated

It was multiplying with U instaed of dividing by U

Author: Viveka Kulharia <vivkul@iitk.ac.in>

Closes #9771 from vivkul/patch-1.

(cherry picked from commit 1429e0a2b562469146b6fa06051c85a00092e5b8)
Signed-off-by: Sean Owen <291c18f3fb7528c712d9098b0e50a515ea0b91d5@cloudera.com>

andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap,andrewor14/iolap