sandbox: Add more dummy functions to mimic other architectures

sandbox: Add more dummy functions to mimic other architectures

This adds more common functions found on other architectures that will
allow for more compile-testing of drivers. These are either dummy
functions as we do not need them or mappings to existing functions,
similar to how other architectures handle it.

Signed-off-by: Tom Rini <trini@konsulko.com>