qede: Fix compilation without QED_RDMA

When CONFIG_QED_RDMA isn't defined, we'd hit the following:

 /include/linux/qed/qede_rdma.h:84:19:
 warning: ‘qede_rdma_dev_add’ used but never defined [enabled by default]
 static inline int qede_rdma_dev_add(struct qede_dev *dev);

Fixes: bbfcd1e8 ("qed*: Set rdma generic functions prefix")
Signed-off-by: Chad Dupuis <chad.dupuis@cavium.com>
Signed-off-by: Yuval Mintz <Yuval.Mintz@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>