i965: Drop a useless ret == 0 check.

i965: Drop a useless ret == 0 check.

Prior to the previous patch, we would pwrite the batchbuffer contents,
and wanted to skip the execbuffer if that failed.  Now that we memcpy,
we don't set ret != 0 on failure anymore, so it will always be 0.

Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>