kbuild: Stop including vmlinux.bz2 in the rpm's

vmlinux.bz2 was added to the rpm packages in 2009 in the
fc370ecf ("kbuild: add vmlinux to kernel rpm") but seemingly hasn't
been used since.

Originally this should have been split up in a seperate debugging
package because it massively increases the size of the generated rpm's
e.g. kernel rpm built using binrpm-pkg on Fedora 36 default 5.19.8 kernel
config and localmodconfig is ~255MB with vmlinux.bz2 and only ~65MB
without it.

Make the kernel built rpms about 4x smaller by not including the unused
vmlinux.bz2 in them.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>