Update language to comply with Android's inclusive language guidance

See https://source.android.com/setup/contribute/respectful-code
for reference.

Test: m ; atest TetheringTests
Bug: 161896447
Change-Id: Idc58697c72fb00896bee00185fefc50c1a24dd35
diff --git a/Tethering/proguard.flags b/Tethering/proguard.flags
index 051fbd1..86b9033 100644
--- a/Tethering/proguard.flags
+++ b/Tethering/proguard.flags
@@ -1,5 +1,5 @@
 # Keep class's integer static field for MessageUtils to parsing their name.
--keep class com.android.networkstack.tethering.Tethering$TetherMasterSM {
+-keep class com.android.networkstack.tethering.Tethering$TetherMainSM {
     static final int CMD_*;
     static final int EVENT_*;
 }