media: cxd2841er: fix 64-bit division on gcc-9

It appears that do_div() once more gets confused by a complex
expression that ends up not quite being constant despite
__builtin_constant_p() thinking it is:

ERROR: modpost: "__aeabi_uldivmod" [drivers/media/dvb-frontends/cxd2841er.ko] undefined!

Use div_u64() instead, forcing the expression to be evaluated
first, and making it a bit more readable.

Cc: Dan Carpenter <dan.carpenter@linaro.org>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Closes: https://lore.kernel.org/linux-media/CA+G9fYvvNm-aYodLaAwwTjEGtX0YxR-1R14FOA5aHKt0sSVsYg@mail.gmail.com/


Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/linux-media/CA+G9fYvvNm-aYodLaAwwTjEGtX0YxR-1R14FOA5aHKt0sSVsYg@mail.gmail.com/


Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
[hverkuil: added Closes tags]