cw1200: Fix a signedness bug in cw1200_load_firmware()

The "priv->hw_type" is an enum and in this context GCC will treat it
as an unsigned int so the error handling will never trigger.

Fixes: a910e4a9 ("cw1200: add driver for the ST-E CW1100 & CW1200 WLAN chipsets")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/st/cw1200/fwio.c

@@ -320,12 +320,12 @@ int cw1200_load_firmware(struct cw1200_common *priv)
 		goto out;
 	}
 
-	priv->hw_type = cw1200_get_hw_type(val32, &major_revision);
-	if (priv->hw_type < 0) {
+	ret = cw1200_get_hw_type(val32, &major_revision);
+	if (ret < 0) {
 		pr_err("Can't deduce hardware type.\n");
-		ret = -ENOTSUPP;
 		goto out;
 	}
+	priv->hw_type = ret;
 
 	/* Set DPLL Reg value, and read back to confirm writes work */
 	ret = cw1200_reg_write_32(priv, ST90TDS_TSET_GEN_R_W_REG_ID,