net: macb: Introduce macb_queue_isr_clear() helper function

net: macb: Introduce macb_queue_isr_clear() helper function

The current implementation includes several occurrences of the
following pattern:
	if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
		queue_writel(queue, ISR, value);

Introduces a helper function to consolidate these repeated code
segments. No functional changes are made.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Link: https://patch.msgid.link/20260402-macb-irq-v2-2-942d98ab1154@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>