ipmi_si: Avoid spurious errors for optional IRQs

Although the IRQ assignment in ipmi_si driver is optional,
platform_get_irq() spews error messages unnecessarily:
  ipmi_si dmi-ipmi-si.0: IRQ index 0 not found

Fix this by switching to platform_get_irq_optional().

Cc: stable@vger.kernel.org # 5.4.x
Cc: John Donnelly <john.p.donnelly@oracle.com>
Fixes: 7723f4c ("driver core: platform: Add an error message to platform_get_irq*()")
Reported-and-tested-by: Patrick Vo <patrick.vo@hpe.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Message-Id: <20200205093146.1352-1-tiwai@suse.de>
Signed-off-by: Corey Minyard <cminyard@mvista.com>

drivers/char/ipmi/ipmi_si_platform.c

@@ -194,7 +194,7 @@ static int platform_ipmi_probe(struct platform_device *pdev)
 	else
 		io.slave_addr = slave_addr;
 
-	io.irq = platform_get_irq(pdev, 0);
+	io.irq = platform_get_irq_optional(pdev, 0);
 	if (io.irq > 0)
 		io.irq_setup = ipmi_std_irq_setup;
 	else
@@ -378,7 +378,7 @@ static int acpi_ipmi_probe(struct platform_device *pdev)
 		io.irq = tmp;
 		io.irq_setup = acpi_gpe_irq_setup;
 	} else {
-		int irq = platform_get_irq(pdev, 0);
+		int irq = platform_get_irq_optional(pdev, 0);
 
 		if (irq > 0) {
 			io.irq = irq;