[build] Don't pad all binary files (dfu.bin is a binary file that will

be included in the final firmware so it does not need to be padded)

build/targets.device.mak

@@ -14,13 +14,9 @@ $(eval $(call rule_for, \
   $$(OBJCOPY) -O ihex $$< $$@ \
 ))
 
-# We pad the device binary files because there was a bug in an older version of
-# the dfu code, and it did not upload properly a binary of length non-multiple
-# of 32 bits.
-#TODO: We over-pad here, pad with the the needed amount of bytes only.
 $(eval $(call rule_for, \
   OBJCOPY, %.bin, %.$$(EXE), \
-  $$(OBJCOPY) -O binary $$< $$@ && printf "\xFF\xFF\xFF\xFF" >> $$@, \
+  $$(OBJCOPY) -O binary $$< $$@, \
   with_local_version \
 ))