kernel: backport "mvmdio avoid error message for optional IRQ"

Rid of kernel error message:
  [    0.780828] orion-mdio d0072004.mdio: IRQ index 0 not found

on Marvell targets backporting the kernel commit fa2632f74e57

Signed-off-by: Daniel González Cabanelas <[email protected]>

target/linux/generic/backport-5.4/751-v5.6-net-mvmdio-avoid-error-message-for-optional-IRQ.patch

@@ -0,0 +1,33 @@
+From fa2632f74e57bbc869c8ad37751a11b6147a3acc Mon Sep 17 00:00:00 2001
+From: Chris Packham <[email protected]>
+Date: Mon, 16 Mar 2020 20:49:07 +1300
+Subject: [PATCH] net: mvmdio: avoid error message for optional IRQ
+
+Per the dt-binding the interrupt is optional so use
+platform_get_irq_optional() instead of platform_get_irq(). Since
+commit 7723f4c5ecdb ("driver core: platform: Add an error message to
+platform_get_irq*()") platform_get_irq() produces an error message
+
+  orion-mdio f1072004.mdio: IRQ index 0 not found
+
+which is perfectly normal if one hasn't specified the optional property
+in the device tree.
+
+Signed-off-by: Chris Packham <[email protected]>
+Reviewed-by: Andrew Lunn <[email protected]>
+Signed-off-by: David S. Miller <[email protected]>
+---
+ drivers/net/ethernet/marvell/mvmdio.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/net/ethernet/marvell/mvmdio.c
++++ b/drivers/net/ethernet/marvell/mvmdio.c
+@@ -347,7 +347,7 @@ static int orion_mdio_probe(struct platf
+ 	}
+ 
+ 
+-	dev->err_interrupt = platform_get_irq(pdev, 0);
++	dev->err_interrupt = platform_get_irq_optional(pdev, 0);
+ 	if (dev->err_interrupt > 0 &&
+ 	    resource_size(r) < MVMDIO_ERR_INT_MASK + 4) {
+ 		dev_err(&pdev->dev,