* Planned London listing comes in jittery markets (Adds book covered): ABU DHABI/LONDON (Reuters) - United Arab Emirates-based Finablr had to cut the price on its initial public offering as the payments and foreign exchange company faced weak investor demand in jittery markets which also rocked ride-hailing app Uber’s Wall Street debut. Finablr was priced at 175 pence per share, the bookrunner said on Tuesday, significantly below an initially anticipated 210-260 pence range, giving the company an implied market value of about 1.23 billion pounds ($1.59 billion).