You should probably use the $(KERNEL_DIR) variable here - that's why it exists.

Also, the kernels are going to be updated to the DSM 4.3 (currently still pointing to DSM 4.1 sources, but 4.3 toolchains - so I'm going to point the kernel Makefiles to branch 3776 (DSM 4.3). I just didn't get around to it until now. You need to make sure your kernel patches are then still required.