Use snprintf instead of sprintf to prevent buffer overruns

Use snprintf instead of sprintf to prevent buffer overruns

In bitops.h, update the TABLE macro to call snprintf(buf, sizeof(buf),
...) rather than unbounded sprintf, ensuring that out-of-range indices
produce a bounded "??%d" string.

In setpci.c, change the device slot formatting from sprintf(slot, ...) to
snprintf(slot, sizeof(slot), ...), capping output to the 16-byte buffer
and avoiding overflow when printing PCI domain, bus, dev, and func
values.

Signed-off-by: Mingjie Shen <shen497@purdue.edu>