net: openvswitch: use div_u64() for 64-by-32 divisions

Compile the kernel for arm 32 platform, the build warning found.
To fix that, should use div_u64() for divisions.
| net/openvswitch/meter.c:396: undefined reference to `__udivdi3'

[add more commit msg, change reported tag, and use div_u64 instead
of do_div by Tonghao]

Fixes: e57358873bb5d6ca ("net: openvswitch: use u64 for meter bucket")
Reported-by: kbuild test robot <[e-mail]>
Signed-off-by: Tonghao Zhang <[e-mail]>
Tested-by: Tonghao Zhang <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/openvswitch/meter.c

···
 		 * Start with a full bucket.
 		 */
 		band->bucket = (band->burst_size + band->rate) * 1000ULL;
-		band_max_delta_t = band->bucket / band->rate;
+		band_max_delta_t = div_u64(band->bucket, band->rate);
 		if (band_max_delta_t > meter->max_delta_t)
 			meter->max_delta_t = band_max_delta_t;
 		band++;