LU-6174 lod: remove incorrect ll_do_div64

LU-6174 lod: remove incorrect ll_do_div64

ll_do_div64() is just a wrapper around do_div() which is handled
incorrectly. do_div() expects a 32 bit value but stripe_count is
cast to 64 bits which is incorrect. Instead lets just avoid
casting and use do_div() directly.

Change-Id: I08601fdf8e9d5fdf26981f073dd602775c12281b
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/38101
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Tested-by: Maloo <maloo@whamcloud.com>