nvme: add a helper to check ctrl sgl support

For various transports such as fc/tcp/pci it is common to check if
NVMe SGLs are supported or not by the controller.

In this preparation patch we add a helper to avoid the open coding of
such checks in the various transport.
Signed-off-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/nvme/host/nvme.h

@@ -869,6 +869,11 @@ static inline void nvme_hwmon_exit(struct nvme_ctrl *ctrl)
 }
 #endif
 
+static inline bool nvme_ctrl_sgl_supported(struct nvme_ctrl *ctrl)
+{
+	return ctrl->sgls & ((1 << 0) | (1 << 1));
+}
+
 u32 nvme_command_effects(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 			 u8 opcode);
 void nvme_execute_passthru_rq(struct request *rq);