dmaengine: fsl-qdma: increase size of 'irq_name'

We seem to have hit warnings of 'output may be truncated' which is fixed
by increasing the size of 'irq_name'

drivers/dma/fsl-qdma.c: In function ‘fsl_qdma_irq_init’:
drivers/dma/fsl-qdma.c:824:46: error: ‘%d’ directive writing between 1 and 11 bytes into a region of size 10 [-Werror=format-overflow=]
  824 |                 sprintf(irq_name, "qdma-queue%d", i);
      |                                              ^~
drivers/dma/fsl-qdma.c:824:35: note: directive argument in the range [-2147483641, 2147483646]
  824 |                 sprintf(irq_name, "qdma-queue%d", i);
      |                                   ^~~~~~~~~~~~~~
drivers/dma/fsl-qdma.c:824:17: note: ‘sprintf’ output between 12 and 22 bytes into a destination of size 20
  824 |                 sprintf(irq_name, "qdma-queue%d", i);
      |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Signed-off-by: Vinod Koul <vkoul@kernel.org>