Add makefile and Makefile.rhelver files owned by the kernel maintainers
Those files are not from the upstream kernel, they are part of the
redhat "sauce" for redhat/ specific make targets and kernel packaging.
Thus make kernel maintainers own them, so any change to them flags
kernel maintainers for review.
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>