import most of the sbmips port into evbmips. the renames are:
- TODO -> evbmips/sbmips/TODO
- sbmips -> evbmips/sbmips
- stand -> evbmips/stand
- conf/files* -> evbmips/conf/files*
- conf/GENERIC* -> evbmips/conf/SBMIPS*

this is not yet ported and will need to be updated, but it's a first step,
and it doesn't handle any include/* issues that need to be dealt with.