Report motion offsets for touchpad swipes

Adds two new axes, AXIS_GESTURE_X_OFFSET and AXIS_GESTURE_Y_OFFSET,
which report the movement of swipe gestures on the touchpad as a
fraction of the touchpad's size.

Bug: 246758376
Test: check axis values come through in a test app
Change-Id: I313410053a8db13273bd05a33d3a6a1f75081dae
diff --git a/libs/input/InputEventLabels.cpp b/libs/input/InputEventLabels.cpp
index 163a2fe..b78fae3 100644
--- a/libs/input/InputEventLabels.cpp
+++ b/libs/input/InputEventLabels.cpp
@@ -391,7 +391,9 @@
     DEFINE_AXIS(GENERIC_13), \
     DEFINE_AXIS(GENERIC_14), \
     DEFINE_AXIS(GENERIC_15), \
-    DEFINE_AXIS(GENERIC_16)
+    DEFINE_AXIS(GENERIC_16), \
+    DEFINE_AXIS(GESTURE_X_OFFSET), \
+    DEFINE_AXIS(GESTURE_Y_OFFSET)
 
 // NOTE: If you add new LEDs here, you must also add them to Input.h
 #define LEDS_SEQUENCE \