drm/rockchip: avoid 64-bit division

drm/rockchip: avoid 64-bit division

Dividing a 64-bit integer prevents building this for 32-bit targets:

ERROR: modpost: "__aeabi_uldivmod" [drivers/gpu/drm/rockchip/rockchipdrm.ko] undefined!

As this function is not performance criticial, just Use the div_u64() helper.

Fixes: 128a9bf8ace2 ("drm/rockchip: Add basic RK3588 HDMI output support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20241018151016.3496613-1-arnd@kernel.org
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>