net: ethernet: micrel: ksz884x.c: Remove unused function

Remove the function port_cfg_dis_learn() that is not used anywhere.

This was partially found by using a static code analysis program called cppcheck.
Signed-off-by: NRickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/micrel/ksz884x.c

@@ -2303,12 +2303,6 @@ static inline int port_chk_force_flow_ctrl(struct ksz_hw *hw, int p)
 
 /* Spanning Tree */
 
-static inline void port_cfg_dis_learn(struct ksz_hw *hw, int p, int set)
-{
-	port_cfg(hw, p,
-		KS8842_PORT_CTRL_2_OFFSET, PORT_LEARN_DISABLE, set);
-}
-
 static inline void port_cfg_rx(struct ksz_hw *hw, int p, int set)
 {
 	port_cfg(hw, p,