Few boards may fail the write actions due to HW limitations (like critical
drivers that disable flash operations). Just retry a few times until success.
In addition, remove the redundant retries in NVStore (not needed now).
Don't allocate the sector map array in this function,
as it was buggy and redundant. Separate user config vs. automatic allocation
cases instead (which was essentially the case anyway).
In addition, fix tests to get over failures in low end boards