idma64: Don't try to serve interrupts when device is powered off

When iDMA 64-bit device is powered off, the IRQ status register
is all 1:s. This is never happen in real case and signalling that
the device is simply powered off. Don't try to serve interrupts
that are not ours.

Fixes: 667dfed98615 ("dmaengine: add a driver for Intel integrated DMA 64-bit")
Reported-by: Heiner Kallweit <[e-mail]>
Closes: https://lore.kernel.org/r/[e-mail]
Tested-by: Heiner Kallweit <[e-mail]>
Signed-off-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/idma64.c

···
 	u32 status_err;
 	unsigned short i;
 
+	/* Since IRQ may be shared, check if DMA controller is powered on */
+	if (status == GENMASK(31, 0))
+		return IRQ_NONE;
+
 	dev_vdbg(idma64->dma.dev, "%s: status=%#x\n", __func__, status);
 
 	/* Check if we have any interrupt from the DMA controller */