Revert "Revert "fastboot: Fix failure when flashing large sparse..."

Revert submission 34724735-432750393

Reason for revert: Still need to land these changes

Reverted changes: /q/submissionid:34724735-432750393

Change-Id: I8b579f232b65dfe38f7a5dc83b1fe3d8643e9598
2 files changed