kconfig-generic: Enable Motorcomm YT6801 ethernet controller

This ethernet controller is found on a handful of Loongson mainboards,
for example the XB612B0 for the 3B6000.

Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8418>

kconfig-generic.toml

@@ -50,6 +50,10 @@ VIDEO_DEV = "m"
 VIDEO_CAMERA_SENSOR = "y"
 VIDEO_OV5675 = "m"
 
+# ethernet controllers, etc.
+["category:ethernet".">=7.0_rc1"."loongarch64"]
+DWMAC_MOTORCOMM = "y"
+
 # input devices
 ["category:input".">=0.0.0"."all"]
 REGULATOR = "y"