Fix for loading progress for mapped files.

- fix the error code clash inside isFullyLoaded,
- work around buggy INCFS_IOC_GET_BLOCK_COUNT ioctl.

Bug: 194143197
Fixes: 194143197
Test: atest IncFsTest
Change-Id: I8ed253f60d7060b0ed2a57ec643b08bb61c6612a
Merged-In: I8ed253f60d7060b0ed2a57ec643b08bb61c6612a
3 files changed