staging: wfx: send just necessary bytes

Size of hif_mib_template_frame must be sufficient to contains bytes
declared by frame_length and cannot exceed 700bytes.

Change the API to reflect that.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200406111756.154086-12-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/hif_api_mib.h

@@ -270,12 +270,14 @@ enum hif_tmplt {
 	HIF_TMPLT_NA     = 0x7
 };
 
+#define HIF_API_MAX_TEMPLATE_FRAME_SIZE 700
+
 struct hif_mib_template_frame {
 	u8     frame_type;
 	u8     init_rate:7;
 	u8     mode:1;
 	__le16 frame_length;
-	u8     frame[700];
+	u8     frame[];
 } __packed;
 
 struct hif_mib_beacon_wake_up_period {

drivers/staging/wfx/hif_tx_mib.c

@@ -148,6 +148,7 @@ int hif_set_template_frame(struct wfx_vif *wvif, struct sk_buff *skb,
 {
 	struct hif_mib_template_frame *arg;
 
+	WARN(skb->len > HIF_API_MAX_TEMPLATE_FRAME_SIZE, "frame is too big");
 	skb_push(skb, 4);
 	arg = (struct hif_mib_template_frame *)skb->data;
 	skb_pull(skb, 4);
@@ -155,7 +156,7 @@ int hif_set_template_frame(struct wfx_vif *wvif, struct sk_buff *skb,
 	arg->frame_type = frame_type;
 	arg->frame_length = cpu_to_le16(skb->len);
 	return hif_write_mib(wvif->wdev, wvif->id, HIF_MIB_ID_TEMPLATE_FRAME,
-			     arg, sizeof(*arg));
+			     arg, sizeof(*arg) + skb->len);
 }
 
 int hif_set_mfp(struct wfx_vif *wvif, bool capable, bool required)