net/mlx5: IPSec, Fix 64-bit division on 32-bit builds

Fix warnings when building 386 kernel:
>> ERROR: "__udivdi3" [drivers/net/ethernet/mellanox/mlx5/core/mlx5_core.ko] undefined!

Fixes: 2ac9cfe7 ("net/mlx5e: IPSec, Add Innova IPSec offload TX data path")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Ilan Tayari <ilant@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/en_accel/ipsec_rxtx.c

@@ -363,6 +363,7 @@ void mlx5e_ipsec_build_inverse_table(void)
 {
 	u16 mss_inv;
 	u32 mss;
+	u64 n;
 
 	/* Calculate 1/x inverse table for use in GSO data path.
 	 * Using this table, we provide the IPSec accelerator with the value of
@@ -372,7 +373,8 @@ void mlx5e_ipsec_build_inverse_table(void)
 	 */
 	mlx5e_ipsec_inverse_table[1] = htons(0xFFFF);
 	for (mss = 2; mss < MAX_LSO_MSS; mss++) {
-		mss_inv = ((1ULL << 32) / mss) >> 16;
+		n = 1ULL << 32;
+		mss_inv = do_div(n, mss) >> 16;
 		mlx5e_ipsec_inverse_table[mss] = htons(mss_inv);
 	}
 }