ssa.c: Eliminate compilation warning (if compiled with -Wformat-security)

The following warning is eliminated:

src/ssa.c: In function âssa_open_devâ:
src/ssa.c:4574:2: warning: format not a string literal and no format arguments [-Wformat-security]
src/ssa.c:4574:2: warning: format not a string literal and no format arguments [-Wformat-security]

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