Add mts ethernet driver for PS5 GBE (0x104d:0x9104) (#8)

Credits:
- slidybat: shared his base, from which a few fixes were merged in
- cow: endless testing, corrections when I went wrong, catching the
  upload-under-load issue, and being an absolute legend

.config

@@ -2402,6 +2402,7 @@ CONFIG_SMSC_PHY=m
 # CONFIG_DP83TG720_PHY is not set
 # CONFIG_VITESSE_PHY is not set
 # CONFIG_XILINX_GMII2RGMII is not set
+CONFIG_MTS=y
 CONFIG_FWNODE_MDIO=y
 CONFIG_ACPI_MDIO=y
 # CONFIG_MDIO_BITBANG is not set