netlink: specs: ethtool: Remove UAPI duplication of phy-upstream enum

The phy-upstream enum is already defined in the ethtool.h UAPI header
and used by the ethtool userspace tool. However, the ethtool spec does
not reference it, causing YNL to auto-generate a duplicate and redundant
enum.

Fix this by updating the spec to reference the existing UAPI enum
in ethtool.h.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20250425171419.947352-1-kory.maincent@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/netlink/specs/ethtool.yaml

@@ -89,8 +89,10 @@ definitions:
           doc: Group of short_detected states
   -
     name: phy-upstream-type
-    enum-name:
+    enum-name: phy-upstream
+    header: linux/ethtool.h
     type: enum
+    name-prefix: phy-upstream
     entries: [ mac, phy ]
   -
     name: tcp-data-split

include/uapi/linux/ethtool_netlink_generated.h

@@ -31,11 +31,6 @@ enum ethtool_header_flags {
 	ETHTOOL_FLAG_STATS = 4,
 };
 
-enum {
-	ETHTOOL_PHY_UPSTREAM_TYPE_MAC,
-	ETHTOOL_PHY_UPSTREAM_TYPE_PHY,
-};
-
 enum ethtool_tcp_data_split {
 	ETHTOOL_TCP_DATA_SPLIT_UNKNOWN,
 	ETHTOOL_TCP_DATA_SPLIT_DISABLED,