misc: microchip: pci1xxxx: Resolve kernel panic during GPIO IRQ handling

Resolve kernel panic caused by improper handling of IRQs while
accessing GPIO values. This is done by replacing generic_handle_irq with
handle_nested_irq.

Fixes: 1f4d8ae231f4 ("misc: microchip: pci1xxxx: Add gpio irq handler and irq helper functions irq_ack, irq_mask, irq_unmask and irq_set_type of irq_chip.")
Cc: stable <[e-mail]>
Signed-off-by: Rengarajan S <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gpio.c

···
 			writel(BIT(bit), priv->reg_base + INTR_STATUS_OFFSET(gpiobank));
 			spin_unlock_irqrestore(&priv->lock, flags);
 			irq = irq_find_mapping(gc->irq.domain, (bit + (gpiobank * 32)));
-			generic_handle_irq(irq);
+			handle_nested_irq(irq);
 		}
 	}
 	spin_lock_irqsave(&priv->lock, flags);