* Q1 net 1.4 bln riyals vs 1.34 bln yr earlier * Analysts had on average forecast 1.52 billion * Co says higher depreciation expenses weigh on results * Revenue 6.24 bln riyals vs 5.63 bln (Adds details) By Matt Smith DUBAI, April 21 (Reuters) - Etihad Etisalat (Mobily), Saudi Arabia's **.2 telecom operator, missed forecasts with a 4.5 percent increase in first-quarter net profit on Monday, as depreciation expenses rose. Mobily, an affiliate of United Arab Emirates-based Etisalat , made a first-quarter net profit of 1.4 billion riyals ($373.3 million), up from 1. ...