plugin: adding SIM_SUPPORT define

In order to run core plugin over large fabrics
using the simulator, SIM_SUPPORT has to be defined.

In such case no ssa devices / ports will be opened
and there will be no data transfering.

This definition should be used for verification
purposes only.

Signed-off-by: Ilya Nelkenbaum <ilyan@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>
core.c: Cosmetic formatting change

Add blank line removed by previous commit ca02131bd05f253f152e1b5166f603d199311bba

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