Build apex_power as module

Change-Id: Ib5339767cc77d69eb85641a33edc4ee331953e85
diff --git a/debian/defconfig b/debian/defconfig
index cd4fc6a..d02a4ee 100644
--- a/debian/defconfig
+++ b/debian/defconfig
@@ -73,7 +73,7 @@
 CONFIG_USB_F_FS=y
 CONFIG_USB_F_ACM=y
 CONFIG_USB_GADGETFS=y
-CONFIG_GOOGLE_APEX_POWER=y
+CONFIG_GOOGLE_APEX_POWER=m
 
 CONFIG_USB_G_HID=y
 CONFIG_USB_SERIAL=y