[yang]Update port yang model, change MTU range to [68,9216] (#12223)

What I did
Filter port invalid MTU configuration

How I did it
Adjust the MTU value to the range of [68,9216]

How to verify it
Use "config interface mtu Ethernet1 40" command to configure the port MTU. The following error will occur in SWSS.

src/sonic-yang-models/tests/yang_model_tests/tests/port.json

@@ -13,6 +13,12 @@
         "eStrKey" : "Pattern",
         "eStr": ["rc"]
     },
+    "PORT_VALID_MTU_TEST_1": {
+        "desc": "PORT_VALID_MTU_TEST_1 no failure."
+    },
+    "PORT_VALID_MTU_TEST_2": {
+        "desc": "PORT_VALID_MTU_TEST_2 no failure."
+    },
     "PORT_VALID_AUTONEG_TEST_1": {
         "desc": "PORT_VALID_AUTONEG_TEST_1 no failure."
     },

src/sonic-yang-models/tests/yang_model_tests/tests_config/port.json

@@ -39,6 +39,36 @@
             }
         }
     },
+    "PORT_VALID_MTU_TEST_1": {
+        "sonic-port:sonic-port": {
+            "sonic-port:PORT": {
+                "PORT_LIST": [
+                    {
+                        "name": "Ethernet8",
+                        "alias": "eth8",
+                        "lanes": "65",
+                        "speed": 25000,
+                        "mtu": 68
+                    }
+                ]
+            }
+        }
+    },
+    "PORT_VALID_MTU_TEST_2": {
+        "sonic-port:sonic-port": {
+            "sonic-port:PORT": {
+                "PORT_LIST": [
+                    {
+                        "name": "Ethernet8",
+                        "alias": "eth8",
+                        "lanes": "65",
+                        "speed": 25000,
+                        "mtu": 9216
+                    }
+                ]
+            }
+        }
+    },
     "PORT_VALID_AUTONEG_TEST_1": {
         "sonic-port:sonic-port": {
             "sonic-port:PORT": {

src/sonic-yang-models/yang-models/sonic-port.yang

@@ -117,7 +117,7 @@ module sonic-port{
 					
 				leaf mtu {
 					type uint16 {
-						range 1..9216;
+						range 68..9216;
 					}
 				}