drm/kms/radeon/agp: Fix warning, format ‘%d’ expects type ‘int’, but argument 4 has type ‘size_t’

- Fix warning by using %zu instead of %d for size_t
- Fix spelling mistake, "to" should be "too".

Signed-off-by: John Kacur <jkacur@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>