NTB: perf: Fix an error code in perf_setup_inbuf()

When the function IS_ALIGNED() returns false, the value of ret is 0.
So, we set ret to -EINVAL to indicate this error.

Clean up smatch warning:
drivers/ntb/test/ntb_perf.c:602 perf_setup_inbuf() warn: missing error
code 'ret'.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

drivers/ntb/test/ntb_perf.c

@@ -598,6 +598,7 @@ static int perf_setup_inbuf(struct perf_peer *peer)
 		return -ENOMEM;
 	}
 	if (!IS_ALIGNED(peer->inbuf_xlat, xlat_align)) {
+		ret = -EINVAL;
 		dev_err(&perf->ntb->dev, "Unaligned inbuf allocated\n");
 		goto err_free_inbuf;
 	}