ceph: cleanup types in striped_read()

commit 688bac461ba3e9d221a879ab40b687f5d7b5b19c upstream.

We pass in a u64 value for "len" and then immediately truncate away the
upper 32 bits.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Sage Weil <sage@inktank.com>
Reviewed-by: Alex Elder <alex.elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>