net: mana: Add support for EQ sharing

The existing code uses (1 + #vPorts * #Queues) MSIXs, which may exceed
the device limit.

Support EQ sharing, so that multiple vPorts (NICs) can share the same
set of MSIXs.

And, report the EQ-sharing capability bit to the host, which means the
host can potentially offer more vPorts and queues to the VM.

Also update the resource limit checking and error handling for better
robustness.

Now, we support up to 256 virtual ports per VF (it was 16/VF), and
support up to 64 queues per vPort (it was 16).

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>