irqchip/loongson-pch-msi: Use bitmap_zalloc() to allocate bitmap

Currently we use bitmap_alloc() to allocate msi bitmap which should be
initialized with zero. This is obviously wrong but it works because msi
can fallback to legacy interrupt mode. So use bitmap_zalloc() instead.

Fixes: 632dcc2c75ef6de3272aa ("irqchip: Add Loongson PCH MSI controller")
Cc: [e-mail]
Signed-off-by: Huacai Chen <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/irqchip/irq-loongson-pch-msi.c

···
 		goto err_priv;
 	}
 
-	priv->msi_map = bitmap_alloc(priv->num_irqs, GFP_KERNEL);
+	priv->msi_map = bitmap_zalloc(priv->num_irqs, GFP_KERNEL);
 	if (!priv->msi_map) {
 		ret = -ENOMEM;
 		goto err_priv;