sdploader_fuzzer: Updated readAt method

exec/s : 1500
Test: ./sdploader_fuzzer
Bug: 240525358

Change-Id: I9303132a82d5cb67ce3eeb6644e20d2ea6f40be4
(cherry picked from commit fcdd5d25edbca10faefb876a719142f22c560f89)
1 file changed