Change grep method

Turns out the UDMP would sometimes shift to having some eth interfaces retain 9216 which would bypass the function. Now this only checks the br interfaces as they appear to inherit the MTU from the interfaces that they are members of.

11-change-mtu.sh

@@ -1,7 +1,6 @@
 #!/bin/sh
 function check_mtu {
-    ip link list | grep -i eth10 | grep -i 'mtu 9216' > /dev/null;
-    ip link list | grep -i switch | grep -i 'mtu 9216' > /dev/null;
+    ip link list | grep -E 'br.:|br..:' | grep 'mtu 9216' > /dev/null;
 }
 while true; do
   if check_mtu; then