linux-imx

rbd: BUG on invalid layout

This shouldn't actually be possible because the layout struct is
constructed from the RBD header and validated then.

[elder@inktank.com: converted BUG() call to equivalent rbd_assert()]

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>