cxgb4: Add support to read actual provisioned resources

In highly constrained resources environments (like the 124VF
T5 and 248VF T6 configurations), PF4 may not have very many
resources at all and we need to adapt to whatever we've been
allocated, this patch adds support to get the provisioned
resources.

Signed-off-by: Casey Leedom <leedom@chelsio.com>
Signed-off-by: Ganesh Goudar <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>