net: stmmac: Unexport stmmac_rx_offset() from stmmac.h

stmmac_rx_offset() is referenced in stmmac_main.c only,
let's move it to stmmac_main.c.

Drop the inline keyword by the way, it is better to let the compiler
to decide.

Compile tested only.
No functional change intended.

Signed-off-by: Furong Xu <0x1207@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250107075448.4039925-1-0x1207@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: Furong Xu

drivers/net/ethernet/stmicro/stmmac/stmmac.h

@@ -416,14 +416,6 @@ static inline bool stmmac_xdp_is_enabled(struct stmmac_priv *priv)
 	return !!priv->xdp_prog;
 }
 
-static inline unsigned int stmmac_rx_offset(struct stmmac_priv *priv)
-{
-	if (stmmac_xdp_is_enabled(priv))
-		return XDP_PACKET_HEADROOM;
-
-	return 0;
-}
-
 void stmmac_disable_rx_queue(struct stmmac_priv *priv, u32 queue);
 void stmmac_enable_rx_queue(struct stmmac_priv *priv, u32 queue);
 void stmmac_disable_tx_queue(struct stmmac_priv *priv, u32 queue);

drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -1315,6 +1315,14 @@ static void stmmac_display_rings(struct stmmac_priv *priv,
 	stmmac_display_tx_rings(priv, dma_conf);
 }
 
+static unsigned int stmmac_rx_offset(struct stmmac_priv *priv)
+{
+	if (stmmac_xdp_is_enabled(priv))
+		return XDP_PACKET_HEADROOM;
+
+	return 0;
+}
+
 static int stmmac_set_bfsize(int mtu, int bufsize)
 {
 	int ret = bufsize;