Add length parameter to format /data

With metadata encryption, if partition is wiped (or) cryptfs failed , it will do format without length which make partition size is grown large to occupy remaining space instead of restricting the Android defined partition size

Bug: 343159184
Test: Add length flag in fstab && fastboot erase userdata && fastboot reboot && df -h /data

Signed-off-by: Ashok Mutyala <quic_amutyala@quicinc.com>
Change-Id: Ifce4b78df5edb899c84a032004895802766cd5cf