iommu/ipmmu-vmsa: Only call platform_get_irq() when interrupt is mandatory

As platform_get_irq() now prints an error when the interrupt does not
exist, calling it gratuitously causes scary messages like:

    ipmmu-vmsa e6740000.mmu: IRQ index 0 not found

Fix this by moving the call to platform_get_irq() down, where the
existence of the interrupt is mandatory.

Fixes: 7723f4c5 ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/ipmmu-vmsa.c

@@ -1086,8 +1086,6 @@ static int ipmmu_probe(struct platform_device *pdev)
 
 	mmu->num_ctx = min(IPMMU_CTX_MAX, mmu->features->number_of_contexts);
 
-	irq = platform_get_irq(pdev, 0);
-
 	/*
 	 * Determine if this IPMMU instance is a root device by checking for
 	 * the lack of has_cache_leaf_nodes flag or renesas,ipmmu-main property.
@@ -1106,6 +1104,7 @@ static int ipmmu_probe(struct platform_device *pdev)
 
 	/* Root devices have mandatory IRQs */
 	if (ipmmu_is_root(mmu)) {
+		irq = platform_get_irq(pdev, 0);
 		if (irq < 0) {
 			dev_err(&pdev->dev, "no IRQ found\n");
 			return irq;