ozone: evdev: Fix repeating the same key after r324081

We broke repeating the same key twice in a row in r324081. Cancelling
repeat must update the repeated key, so that we can tell that we need
to start a new repeat for that key in UpdateKeyRepeat if it's pressed
again.

TEST=Repeat the same key twice in a row on link
BUG=473446

Review URL: https://codereview.chromium.org/1074503002

Cr-Commit-Position: refs/heads/master@{#324263}

ui/events/ozone/evdev/keyboard_evdev.cc

@@ -156,6 +156,7 @@ void KeyboardEvdev::StartKeyRepeat(unsigned int key) {
 }
 
 void KeyboardEvdev::StopKeyRepeat() {
+  repeat_key_ = KEY_RESERVED;
   repeat_sequence_++;
 }