plugin: Align LFT block size macro used

 - UMAD_LEN_SMP_DATA is used in core.c, ssa_smdb.[c,h]

 - IB_SMP_DATA_SIZE is used in the rest of the plugin source files

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