If the object is bigger than the entire aperture, reject it early
before evicting everything in a vain attempt to find space.

v2: Use E2BIG as suggested by Owain G. Ainsworth.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
Signed-off-by: NEric Anholt <eric@anholt.net>