This reverts commit ebbe59b205.
It caused difficulties with packaging the module which require relevant
knowledge to resolve. So far it seems simpler to revert this
modification.
Using the whole Makefile results in DKMS running commands unrelated to
the build process (like git commands) which only produce confusing error
output.
Just write `obj-m += nct6687.o` to the Makefile for DKMS as that's the
only thing necessary for it to work.
This also gets rid of `MAKE[0]` in `dkms.conf`.
`/etc/fedora-release` doesn't exist on non-Fedora systems, but `sed` is
used on it unconditionally. Redirect error to `/dev/null` and give the
variable a reasonable value for systems without the file.
