intel: Suppress the error return from setting domains after mapping.

If the mapping succeeds we have a valid pointer. If setting the domain
failures we may incur cache corruption. However the usual failure mode
is because of a hung GPU, in which case it is preferable to ignore the
minor error from setting the domain and continue on oblivious. If
these errors persist, we should rate limit the warning [or even just
remove it].

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>