Correction in logic of roundend size calculation of SD card

API FileUtils.roundStorageSize() rounded up the Storage size incorrectly
and caused the storage total size to be displayed twice the actual capacity
in storage Settings application.
Modifications done to appropriately roundup the storage size in the
multiple of power of 2 by making the loop iterations to be controlled by
1024 instead of 1000.

Test: Verified with the particular SD card with which bug reported.
Change-Id: I8f92248a457d6ac507d092df46e1cb0daaa55134