Sorry, but a statement like that is just useless.
How is it broken?
And you won’t need to install drm-kmp-default at all with the newer kernel, as it just contains some graphics drivers from kernel 4.9 (which are useless and shouldn’t be installed if you want to use nvidia anyway).
As I said, make sure that kernel-devel 4.15.x and kernel-default-devel is installed.
Then the nvidia package should install just fine.
If not, please post the error messages.
Otherwise it’s hard (or actually impossible) to help anyway.