staging: mt7621-dts: use trgmii on gmac0 and enable flow control on port@6

Change phy-mode of gmac0 to trgmii to match the other side, port@6.

Flow control needs to be enabled on both sides to work.
It is already enabled on gmac0, enable it on port@6 too.
Reviewed-by: NSergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: NArınç ÜNAL <arinc.unal@arinc9.com>
Link: https://lore.kernel.org/r/20220125153903.1469-4-arinc.unal@arinc9.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-dts/mt7621.dtsi

@@ -328,7 +328,7 @@
 		gmac0: mac@0 {
 			compatible = "mediatek,eth-mac";
 			reg = <0>;
-			phy-mode = "rgmii";
+			phy-mode = "trgmii";
 
 			fixed-link {
 				speed = <1000>;
@@ -412,6 +412,7 @@
 						fixed-link {
 							speed = <1000>;
 							full-duplex;
+							pause;
 						};
 					};
 				};