dmaengine: cirrus: use snprintf() to calm down gcc 13.3.0

dmaengine: cirrus: use snprintf() to calm down gcc 13.3.0

Even though it's a false positive (highest channel number is "9"), refer to
"struct ep93xx_edma_data edma_m2p", we can avoid new warning by using
snprintf().

   drivers/dma/ep93xx_dma.c: In function 'ep93xx_dma_of_probe':
>> drivers/dma/ep93xx_dma.c:1365:51: warning: '%u' directive writing between 1 and 8 bytes into a region of size 2 [-Wformat-overflow=]
    1365 |                         sprintf(dma_clk_name, "m2p%u", i);
         |                                                   ^~
   drivers/dma/ep93xx_dma.c:1365:47: note: directive argument in the range [0, 16777216]
    1365 |                         sprintf(dma_clk_name, "m2p%u", i);
         |                                               ^~~~~~~
   drivers/dma/ep93xx_dma.c:1365:25: note: 'sprintf' output between 5 and 12 bytes into a destination of size 5
    1365 |                         sprintf(dma_clk_name, "m2p%u", i);
         |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 4e8ad5ed845b ("dmaengine: cirrus: Convert to DT for Cirrus EP93xx")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409122133.NctarRoK-lkp@intel.com/
Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>