common/mlx5: fix pointer cast on Windows

common/mlx5: fix pointer cast on Windows

While compiling with clang 11 the callers of the
__mlx5_bit_off macro warns on the cast of pointers to
unsigned long which is a smaller int type in Windows.

warning: cast to smaller integer type 'unsigned long'
from 'u8 (*)[16]' [-Wpointer-to-int-cast]

To resolve it the type is changed to uintptr_t to be
compatible for both Linux and Windows.

Fixes: 865a0c15672c ("net/mlx5: add Direct Verbs prepare function")
Cc: stable@dpdk.org
Signed-off-by: Tal Shnaiderman <talshn@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>