The script splits 'sfdisk' output wrongly in blank spaces leading to
failures when partition id is greater than 10, e.g.:
"/dev/sda10: start= ...".
This fix splits the output on ":" and trims trailing space when
partition id is less than 10, e.g.: "/dev/sda1 : start= ...".
Change-Id: I23f4b747fc0a86713cb912afc5d193398e6a597b
Closes-Bug: 1581699