staging: vt6656: add error code handling to unused variable

Add error code handling to unused 'ret' variable that was never used.
Return an error code from functions called within vnt_radio_power_on.

Issue reported by coccinelle (coccicheck).
Suggested-by: Quentin Deslandes <quentin.deslandes@itdev.co.uk>
Suggested-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: Quentin Deslandes <quentin.deslandes@itdev.co.uk>
Signed-off-by: John B. Wyatt IV <jbwyatt4@gmail.com>
Reviewed-by: Stefano Brivio <sbrivio@redhat.com>
Link: https://lore.kernel.org/r/20200330233900.36938-1-jbwyatt4@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6656/card.c

@@ -723,9 +723,13 @@ int vnt_radio_power_on(struct vnt_private *priv)
 {
 	int ret = 0;
 
-	vnt_exit_deep_sleep(priv);
+	ret = vnt_exit_deep_sleep(priv);
+	if (ret)
+		return ret;
 
-	vnt_mac_reg_bits_on(priv, MAC_REG_HOSTCR, HOSTCR_RXON);
+	ret = vnt_mac_reg_bits_on(priv, MAC_REG_HOSTCR, HOSTCR_RXON);
+	if (ret)
+		return ret;
 
 	switch (priv->rf_type) {
 	case RF_AL2230:
@@ -734,14 +738,14 @@ int vnt_radio_power_on(struct vnt_private *priv)
 	case RF_VT3226:
 	case RF_VT3226D0:
 	case RF_VT3342A0:
-		vnt_mac_reg_bits_on(priv, MAC_REG_SOFTPWRCTL,
-				    (SOFTPWRCTL_SWPE2 | SOFTPWRCTL_SWPE3));
-		break;
+		ret = vnt_mac_reg_bits_on(priv, MAC_REG_SOFTPWRCTL,
+					  (SOFTPWRCTL_SWPE2 |
+					   SOFTPWRCTL_SWPE3));
+		if (ret)
+			return ret;
 	}
 
-	vnt_mac_reg_bits_off(priv, MAC_REG_GPIOCTL1, GPIO3_INTMD);
-
-	return ret;
+	return vnt_mac_reg_bits_off(priv, MAC_REG_GPIOCTL1, GPIO3_INTMD);
 }
 
 void vnt_set_bss_mode(struct vnt_private *priv)