arch/mips: remove deprecated mips1/2/3/4 support

Remove the support for generating mips1/2/3/4 code since it has been
deprecated for more than a year now.
Also remove the unnecessary kludges in packages for it.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Acked-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>