block: merge __bio_map_kern into bio_map_kern
block: merge __bio_map_kern into bio_map_kern

This saves a little code, and allow to simplify the error handling.

Signed-off-by: Christoph Hellwig <923f7720577207a44b32e59bbfbea59d27f1ae8e@lst.de>
Reviewed-by: Ming Lei <572efd9047f12626ad5bcb995a452788646858f3@gmail.com>
Signed-off-by: Jens Axboe <cd8c6775e60d6f67a6984377324e5290df3d5358@fb.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs