misc: microchip: pci1xxxx: Fix incorrect IRQ status handling during ack

Under irq_ack, pci1xxxx_assign_bit reads the current interrupt status,
modifies and writes the entire value back. Since, the IRQ status bit
gets cleared on writing back, the better approach is to directly write
the bitmask to the register in order to preserve the value.

Fixes: 1f4d8ae ("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 <stable@kernel.org>
Signed-off-by: Rengarajan S <rengarajan.s@microchip.com>
Link: https://lore.kernel.org/r/20250313170856.20868-3-rengarajan.s@microchip.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: RengarajanSS

drivers/misc/mchp_pci1xxxx/mchp_pci1xxxx_gpio.c

@@ -168,7 +168,7 @@ static void pci1xxxx_gpio_irq_ack(struct irq_data *data)
 	unsigned long flags;
 
 	spin_lock_irqsave(&priv->lock, flags);
-	pci1xxx_assign_bit(priv->reg_base, INTR_STAT_OFFSET(gpio), (gpio % 32), true);
+	writel(BIT(gpio % 32), priv->reg_base + INTR_STAT_OFFSET(gpio));
 	spin_unlock_irqrestore(&priv->lock, flags);
 }