lib: Correct null pointer check

In order to prevent a possible null pointer dereference, return early if
either one of 'in' or 'data' is null.

Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>

lib/sbi/sbi_tlb.c

@@ -66,7 +66,7 @@ static int sbi_tlb_fifo_update_cb(void *in, void *data)
 	struct sbi_tlb_info *next;
 	int ret = SBI_FIFO_UNCHANGED;
 
-	if (!in && !!data)
+	if (!in || !data)
 		return ret;
 
 	curr = (struct sbi_tlb_info *)data;