bump updater API version to 3; deprecate firmware update command

Remove support for the HTC-specific "firmware" update command and the
corresponding edify function write_firmware_update().  This
functionality is now done by an edify extension library that lives in
vendor/htc.

Change-Id: I80858951ff10ed8dfff98aefb796bef009e05efb
diff --git a/Android.mk b/Android.mk
index e89b225..5f74064 100644
--- a/Android.mk
+++ b/Android.mk
@@ -9,7 +9,6 @@
 LOCAL_SRC_FILES := \
     recovery.c \
     bootloader.c \
-    firmware.c \
     install.c \
     roots.c \
     ui.c \
@@ -22,7 +21,7 @@
 
 LOCAL_FORCE_STATIC_EXECUTABLE := true
 
-RECOVERY_API_VERSION := 2
+RECOVERY_API_VERSION := 3
 LOCAL_CFLAGS += -DRECOVERY_API_VERSION=$(RECOVERY_API_VERSION)
 
 # This binary is in the recovery ramdisk, which is otherwise a copy of root.