uapi: fix rdma/mlx5-abi.h userspace compilation errors

Consistently use types from linux/types.h to fix the following
rdma/mlx5-abi.h userspace compilation errors:

/usr/include/rdma/mlx5-abi.h:69:25: error: 'u64' undeclared here (not in a function)
  MLX5_LIB_CAP_4K_UAR = (u64)1 << 0,
/usr/include/rdma/mlx5-abi.h:69:29: error: expected ',' or '}' before numeric constant
  MLX5_LIB_CAP_4K_UAR = (u64)1 << 0,

Include <linux/if_ether.h> to fix the following rdma/mlx5-abi.h
userspace compilation error:

/usr/include/rdma/mlx5-abi.h:286:12: error: 'ETH_ALEN' undeclared here (not in a function)
  __u8 dmac[ETH_ALEN];

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>