net/mlx5: Fix duplicate included vhca_event.h

Clean up the following includecheck warning:

./drivers/net/ethernet/mellanox/mlx5/core/sf/hw_table.c: vhca_event.h is
included more than once.

No functional change.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>