datasets: fix cppcheck warning

datasets: fix cppcheck warning

src/datasets.c:107:17: error: Uninitialized variable: hash [uninitvar]
    memcpy(out, hash, outs);
                ^
src/datasets.c:93:26: note: Assuming condition is false
    for (x = 0, i = 0; i < ins; i+=2, x++) {
                         ^
src/datasets.c:107:17: note: Uninitialized variable: hash
    memcpy(out, hash, outs);
                ^

Bug: #5291.
(cherry picked from commit ea2d0ecf08842d52f77d1a88a184a85960999e1e)