Remove REMAKE_INITRD

The option has been deprecated in dkms and will break packaging in
future versions. See https://github.com/dell/dkms/commit/7114c62

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Amanakis <gamanakis@gmail.com>
Signed-off-by: jokersus <jokersus.cava@gmail.com>
Closes #12781