qed: Revise alloc/setup/free flow

Re-organize the logic that allocates and frees memory of various
sub-components of the hw-function -

 a. No need to pass pointers to said structure as parameters;
    The internal logic knows exactly where to find/set the data.

 b. Nullify pointers after cleanup to prevent possible errors to
    re-entrant code.

Signed-off-by: Tomer Tayar <Tomer.Tayar@cavium.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/qlogic/qed/qed_mcp.c b/drivers/net/ethernet/qlogic/qed/qed_mcp.c
index 7266b36..b32e819 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_mcp.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_mcp.c
@@ -177,6 +177,7 @@ int qed_mcp_free(struct qed_hwfn *p_hwfn)
 	}
 
 	kfree(p_hwfn->mcp_info);
+	p_hwfn->mcp_info = NULL;
 
 	return 0;
 }