i2c: pca-platform: Use platform_irq_get_optional

The interrupt is not required so use platform_irq_get_optional() to
avoid error messages like

i2c-pca-platform 22080000.i2c: IRQ index 0 not found

Signed-off-by: Chris Packham <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

drivers/i2c/busses/i2c-pca-platform.c

···
 	int ret = 0;
 	int irq;
 
-	irq = platform_get_irq(pdev, 0);
+	irq = platform_get_irq_optional(pdev, 0);
 	/* If irq is 0, we do polling. */
 	if (irq < 0)
 		irq = 0;