drm/sun4i: hdmi: Fix u64 div on 32bit arch

drm/sun4i: hdmi: Fix u64 div on 32bit arch

Commit 358e76fd613a ("drm/sun4i: hdmi: Consolidate atomic_check and
mode_valid") changed the clock rate from an unsigned long to an unsigned
long long resulting in a a 64-bit division that might not be supported
on all platforms.

The resulted in compilation being broken at least for m68k, xtensa and
some arm configurations, at least.

Fixes: 358e76fd613a ("drm/sun4i: hdmi: Consolidate atomic_check and mode_valid")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Closes: https://lore.kernel.org/r/CA+G9fYvG9KE15PGNoLu+SBVyShe+u5HBLQ81+kK9Zop6u=ywmw@mail.gmail.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202403011839.KLiXh4wC-lkp@intel.com/
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20240304091225.366325-1-mripard@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>