dmaengine: xilinx: xdma: Fix interrupt vector setting

A couple of hardware registers need to be set to reflect which
interrupts have been allocated to the device. Each register is 32-bit
wide and can receive four 8-bit values. If we provide any other interrupt
number than four, the irq_num variable will never be 0 within the while
check and the while block will loop forever.

There is an easy way to prevent this: just break the for loop
when we reach "irq_num == 0", which anyway means all interrupts have
been processed.

Cc: stable@vger.kernel.org
Fixes: 17ce2522

 ("dmaengine: xilinx: xdma: Add xilinx xdma driver")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://lore.kernel.org/r/20230731101442.792514-2-miquel.raynal@bootlin.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>