nvethernet: runtime power gating/ungating for MGBE

Adds support for runtime power gating/ungating
for MGBE through Linux PM runtime API's.

It requires power-domains DT entry to be part
of ethernet DT node.

Bug 200740290

Change-Id: I95727e8cbb5615d01603f4bb456253f05ff32d42
Signed-off-by: Bhadram Varka <vbhadram@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvidia/+/2548337
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>
Reviewed-by: svcacv <svcacv@nvidia.com>
Reviewed-by: svc_kernel_abi <svc_kernel_abi@nvidia.com>
Reviewed-by: Srinivas Ramachandran <srinivasra@nvidia.com>
Reviewed-by: Sachin Nikam <snikam@nvidia.com>
Reviewed-by: Narayan Reddy <narayanr@nvidia.com>
Reviewed-by: Bitan Biswas <bbiswas@nvidia.com>
Reviewed-by: Aleksandr Frid <afrid@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
GVS: Gerrit_Virtual_Submit

drivers/net/ethernet/nvidia/nvethernet/ether_linux.h

@@ -22,6 +22,7 @@
 #include <linux/platform_device.h>
 #include <linux/etherdevice.h>
 #include <linux/net_tstamp.h>
+#include <linux/pm_runtime.h>
 #include <linux/interrupt.h>
 #include <linux/workqueue.h>
 #include <linux/spinlock.h>