mlx4_core: Read extended capabilities into the flags field

Query another dword containing up to 32 extended device capabilities
and merge it into struct mlx4_caps.flags.  Update the code that
handles the current extended device capabilities (e.g UDP RSS, WoL,
vep steering, etc) to use the extended device cap flags field instead
of a field per extended capability.  Initial patch done by Eli Cohen
<eli@mellanox.co.il>.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.co.il>
Signed-off-by: Roland Dreier <roland@purestorage.com>