ssa_comparison.c: LFT memory allocation fix

In case of LFT changed records (blocks / tops), memory
reallocated according to the number of new records that didn't
exist before in SMDB.

Signed-off-by: Ilya Nelkenbaum <ilyan@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>