[PATCH] staging: ozwpan: Fix build warning.

[Anca Emanuel]

Why do not use div_u64() ?

[quote]unsigned 64bit divide with 32bit divisor

This is the most common 64bit divide and should be used if possible,
as many 32bit archs can optimize this variant better than a full 64bit
divide.
[/quote]

> -               ep->credit += timespec_to_ns(&delta) / NSEC_PER_MSEC;
> +               ep->credit += div64_u64(timespec_to_ns(&delta), NSEC_PER_MSEC);