net: macb: replace macb_writel() call by queue_writel() to update queue ISR

macb_interrupt() should not use macb_writel(bp, ISR, <value>) but only
queue_writel(queue, ISR, <value>).

There is one IRQ and one set of {ISR, IER, IDR, IMR} [1] registers per
queue on gem hardware, though only queue0 is actually used for now to
receive frames: other queues can already be used to transmit frames.

The queue_readl() and queue_writel() helper macros are designed to access
the relevant IRQ registers.

[1]
ISR: Interrupt Status Register
IER: Interrupt Enable Register
IDR: Interrupt Disable Register
IMR: Interrupt Mask Register

Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>
Fixes: bfbb92c4 ("net: macb: Handle the RXUBR interrupt on all devices")
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>