Add Volantis-only keymap APK.

The Volantis keyboard cover has only 47 keys, instead of the typical
48, which means it requires a custom key mapping in order to work
properly. Since the cover is Volantis specific, however, it should
only be included in Volantis builds and nothing else, hence its
presence in the overlay rather than the framework tree.

Change-Id: I8bd6ec90f1a407b36f9b4fe374c40a4104b2fd31
diff --git a/device.mk b/device.mk
index c25cee5..faf0b86 100644
--- a/device.mk
+++ b/device.mk
@@ -225,6 +225,10 @@
 PRODUCT_PACKAGES += \
     sound_trigger.primary.flounder
 
+# for keyboard key mappings
+PRODUCT_PACKAGES += \
+	VolantisKeyboard
+
 # Allows healthd to boot directly from charger mode rather than initiating a reboot.
 PRODUCT_DEFAULT_PROPERTY_OVERRIDES += \
     ro.enable_boot_charger_mode=1