p54: potential signedness issue in p54_parse_rssical()

"entries" is unsigned here, so it is never less than zero. In theory,
len could be less than offset so I have added a check for that.

Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Christian Lamparter <[e-mail]>
Signed-off-by: John W. Linville <[e-mail]>

drivers/net/wireless/p54/eeprom.c

···
 		entries = (len - offset) /
 			sizeof(struct pda_rssi_cal_ext_entry);
 
-		if ((len - offset) % sizeof(struct pda_rssi_cal_ext_entry) ||
-		    entries <= 0) {
+		if (len < offset ||
+		    (len - offset) % sizeof(struct pda_rssi_cal_ext_entry) ||
+		    entries == 0) {
 			wiphy_err(dev->wiphy, "invalid rssi database.\n");
 			goto err_data;
 		}