Abhinav gave correct solution, but there are minor syntax errors in it.
SELECT CAST(LoggedIn AS DATE) LoggedIn
,COUNT(LoggedInFrom) AS Device
FROM User_log_Info
WHERE LoggedIn BETWEEN '03/20/2015 00:00:00' AND '03/22/2015 23:59:59'
AND LoggedInFrom = 1
GROUP BY CAST(LoggedIn AS DATE)
ORDER BY LoggedIn ASC
Note that I changed one condition LoggedInFrom =
1 to get data as per the sample provided.