dmaengine: xilinx: xdma: Workaround truncation compilation error

Increase length to be copied to be large enough to overcome the
following compilation error. The buf is large enough for this purpose.

drivers/dma/xilinx/xilinx_dpdma.c: In function ‘xilinx_dpdma_debugfs_desc_done_irq_read’:
drivers/dma/xilinx/xilinx_dpdma.c:313:39: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=]
  313 |         snprintf(buf, out_str_len, "%d",
      |                                       ^
drivers/dma/xilinx/xilinx_dpdma.c:313:9: note: ‘snprintf’ output between 2 and 6 bytes into a destination of size 5
  313 |         snprintf(buf, out_str_len, "%d",
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  314 |                  dpdma_debugfs.xilinx_dpdma_irq_done_count);
      |                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20231222094017.731917-1-vkoul@kernel.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/xilinx/xilinx_dpdma.c

@@ -309,7 +309,7 @@ static ssize_t xilinx_dpdma_debugfs_desc_done_irq_read(char *buf)
 
 	out_str_len = strlen(XILINX_DPDMA_DEBUGFS_UINT16_MAX_STR);
 	out_str_len = min_t(size_t, XILINX_DPDMA_DEBUGFS_READ_MAX_SIZE,
-			    out_str_len);
+			    out_str_len + 1);
 	snprintf(buf, out_str_len, "%d",
 		 dpdma_debugfs.xilinx_dpdma_irq_done_count);