irqchip/sifive-plic: Return error code on failure

Set error to -ENOMEM if kcalloc() fails or if irq_domain_add_linear()
fails inside of plic_probe() instead of returning 0.

Fixes: 4d936f10 ("irqchip/sifive-plic: Probe plic driver early for Allwinner D1 platform")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20240903-correct_error_codes_sifive_plic-v1-1-d929b79663a2@rivosinc.com
Closes: https://lore.kernel.org/r/202409031122.yBh8HrxA-lkp@intel.com/

drivers/irqchip/irq-sifive-plic.c

@@ -626,8 +626,10 @@ static int plic_probe(struct fwnode_handle *fwnode)
 
 		handler->enable_save = kcalloc(DIV_ROUND_UP(nr_irqs, 32),
 					       sizeof(*handler->enable_save), GFP_KERNEL);
-		if (!handler->enable_save)
+		if (!handler->enable_save) {
+			error = -ENOMEM;
 			goto fail_cleanup_contexts;
+		}
 done:
 		for (hwirq = 1; hwirq <= nr_irqs; hwirq++) {
 			plic_toggle(handler, hwirq, 0);
@@ -639,8 +641,10 @@ static int plic_probe(struct fwnode_handle *fwnode)
 
 	priv->irqdomain = irq_domain_create_linear(fwnode, nr_irqs + 1,
 						   &plic_irqdomain_ops, priv);
-	if (WARN_ON(!priv->irqdomain))
+	if (WARN_ON(!priv->irqdomain)) {
+		error = -ENOMEM;
 		goto fail_cleanup_contexts;
+	}
 
 	/*
 	 * We can have multiple PLIC instances so setup global state