mailbox: tegra: Fix superfluous IRQ error message

Commit 7723f4c5ec ("driver core: platform: Add an error message to
platform_get_irq*()") added an error message to avoid drivers having
to print an error message when IRQ lookup fails. However, there are
some cases where IRQs are optional and so new optional versions of
the platform_get_irq*() APIs have been added for these cases.

The IRQs for Tegra HSP module are optional because not all instances
of the module have the doorbell and all of the shared interrupts.
Hence, since the above commit was applied the following error messages
are now seen on Tegra194 ...

 ERR KERN tegra-hsp c150000.hsp: IRQ doorbell not found
 ERR KERN tegra-hsp c150000.hsp: IRQ shared0 not found

The Tegra HSP driver deliberately does not fail if these are not found
and so fix the above errors by updating the Tegra HSP driver to use
the platform_get_irq_byname_optional() API.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20191011083459.11551-1-jonathanh@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mailbox/tegra-hsp.c

@@ -657,7 +657,7 @@ static int tegra_hsp_probe(struct platform_device *pdev)
 	hsp->num_db = (value >> HSP_nDB_SHIFT) & HSP_nINT_MASK;
 	hsp->num_si = (value >> HSP_nSI_SHIFT) & HSP_nINT_MASK;
 
-	err = platform_get_irq_byname(pdev, "doorbell");
+	err = platform_get_irq_byname_optional(pdev, "doorbell");
 	if (err >= 0)
 		hsp->doorbell_irq = err;
 
@@ -677,7 +677,7 @@ static int tegra_hsp_probe(struct platform_device *pdev)
 			if (!name)
 				return -ENOMEM;
 
-			err = platform_get_irq_byname(pdev, name);
+			err = platform_get_irq_byname_optional(pdev, name);
 			if (err >= 0) {
 				hsp->shared_irqs[i] = err;
 				count++;