Don't require vendor makefile

This reverts a change to device.mk made in change I1e8b85d83a924ab973369163b1eae722dbace839

The problem with requiring vendor makefiles is that the initial run of `breakfast crespo` fails because this file does not exist.

Change-Id: I50bcf86381bc7895b60ad69a27262af29d6fd9be
Merge branch 'cm-10.2' into martincz