ceph: propagate layout error on osd request creation

If we are creating an osd request and get an invalid layout, return
an EINVAL to the caller.  We switch up the return to have an error
code instead of NULL implying -ENOMEM.

Signed-off-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <elder@inktank.com>
(cherry picked from commit 6816282dab3a72efe8c0d182c1bc2960d87f4322)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>