ui: Check for bootreason=recovery_ui.

Some wear bootloaders are passing bootreason=recovery_ui when booting
into recovery from fastboot, or via 'adb reboot recovery'. Allow turning
on text mode with a swipe for such a bootreason. Since we will turn on
text mode automatically for debuggable builds, this bootreason mainly
handles the case for user builds.

Note this change only applies to devices that allow touch screen inputs.

Bug: 36169090
Test: Build and boot into user build recovery image. Toggle on text mode
      with a swipe.
Change-Id: I55f19aed7b210352f8370de19935b4772cc12095
diff --git a/ui.h b/ui.h
index 5cda7af..3d9afec 100644
--- a/ui.h
+++ b/ui.h
@@ -170,6 +170,7 @@
   int touch_start_Y_;
   bool touch_finger_down_;
   bool touch_swiping_;
+  bool is_bootreason_recovery_ui_;
 
   struct key_timer_t {
     RecoveryUI* ui;