net: pcs: pcs-mtk-lynxi: report in-band capability for 2500Base-X

It turns out that 2500Base-X actually works fine with in-band status on
MediaTek's LynxI PCS -- I wrongly concluded it didn't because it is
broken in all the copper SFP modules and GPON sticks I used for testing.

Hence report LINK_INBAND_ENABLE also for 2500Base-X mode.

This reverts most of commit a003c38d9bbb ("net: pcs: pcs-mtk-lynxi:
correctly report in-band status capabilities").

The removal of the QSGMII interface mode was correct and is left
untouched.

Link: https://github.com/openwrt/openwrt/issues/21436
Fixes: a003c38d9bbb ("net: pcs: pcs-mtk-lynxi: correctly report in-band status capabilities")
Signed-off-by: Daniel Golle <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/pcs/pcs-mtk-lynxi.c

···
 {
 	switch (interface) {
 	case PHY_INTERFACE_MODE_1000BASEX:
+	case PHY_INTERFACE_MODE_2500BASEX:
 	case PHY_INTERFACE_MODE_SGMII:
 		return LINK_INBAND_DISABLE | LINK_INBAND_ENABLE;
-
-	case PHY_INTERFACE_MODE_2500BASEX:
-		return LINK_INBAND_DISABLE;
 
 	default:
 		return 0;