staging: rtl8712: Drop get_recvframe_data()

As done for rtl8723bs and r8188eu, drop get_recvframe_data(), as it
introduces an impossible value (NULL) for the compiler to check code
paths against which could result in nonsensical warnings.

Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Florian Schilhabel <florian.c.schilhabel@googlemail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: Zhansaya Bagdauletkyzy <zhansayabagdaulet@gmail.com>
Cc: Ivan Safonov <insafonov@gmail.com>
Cc: linux-staging@lists.linux.dev
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220118193327.2822099-4-keescook@chromium.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/rtl871x_recv.c

@@ -234,7 +234,7 @@ union recv_frame *r8712_portctrl(struct _adapter *adapter,
 	u16 ether_type;
 
 	pstapriv = &adapter->stapriv;
-	ptr = get_recvframe_data(precv_frame);
+	ptr = precv_frame->u.hdr.rx_data;
 	pfhdr = &precv_frame->u.hdr;
 	psta_addr = pfhdr->attrib.ta;
 	psta = r8712_get_stainfo(pstapriv, psta_addr);
@@ -593,7 +593,7 @@ int r8712_wlanhdr_to_ethhdr(union recv_frame *precvframe)
 	struct _adapter	*adapter = precvframe->u.hdr.adapter;
 	struct mlme_priv *pmlmepriv = &adapter->mlmepriv;
 
-	u8 *ptr = get_recvframe_data(precvframe); /*point to frame_ctrl field*/
+	u8 *ptr = precvframe->u.hdr.rx_data; /*point to frame_ctrl field*/
 	struct rx_pkt_attrib *pattrib = &precvframe->u.hdr.attrib;
 
 	if (pattrib->encrypt)

drivers/staging/rtl8712/rtl871x_recv.h

@@ -139,14 +139,6 @@ static inline u8 *get_rxmem(union recv_frame *precvframe)
 	return precvframe->u.hdr.rx_head;
 }
 
-static inline u8 *get_recvframe_data(union recv_frame *precvframe)
-{
-	/* always return rx_data */
-	if (!precvframe)
-		return NULL;
-	return precvframe->u.hdr.rx_data;
-}
-
 static inline u8 *recvframe_pull(union recv_frame *precvframe, sint sz)
 {
 	/* used for extract sz bytes from rx_data, update rx_data and return