net: phylink: allow half-duplex modes with RATE_MATCH_PAUSE

PHYs performing rate-matching using MAC-side flow-control always
perform duplex-matching as well in case they are supporting
half-duplex modes at all.
No longer remove half-duplex modes from their capabilities.

Suggested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/b157c0c289cfba024039a96e635d037f9d946745.1728617993.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/phylink.c

@@ -599,15 +599,8 @@ static unsigned long phylink_get_capabilities(phy_interface_t interface,
 		 * max speed at full duplex.
 		 */
 		if (mac_capabilities &
-		    phylink_cap_from_speed_duplex(max_speed, DUPLEX_FULL)) {
-			/* Although a duplex-matching phy might exist, we
-			 * conservatively remove these modes because the MAC
-			 * will not be aware of the half-duplex nature of the
-			 * link.
-			 */
+		    phylink_cap_from_speed_duplex(max_speed, DUPLEX_FULL))
 			matched_caps = GENMASK(__fls(caps), __fls(MAC_10HD));
-			matched_caps &= ~(MAC_1000HD | MAC_100HD | MAC_10HD);
-		}
 		break;
 	}
 	case RATE_MATCH_CRS: