drm/amdgpu/jpeg: Fix sprintf buffer overflow warning in jpeg_v2_5

drm/amdgpu/jpeg: Fix sprintf buffer overflow warning in jpeg_v2_5

Replace sprintf() with snprintf() to fix the -Werror=format-overflow
warning when building with allmodconfig:

  drivers/gpu/drm/amd/amdgpu/jpeg_v2_5.c:152:47: error: '%d' directive
  writing between 1 and 11 bytes into a region of size 7
  [-Werror=format-overflow=]
    152 |                 sprintf(ring->name, "jpeg_dec_%d", i);

The ring->name buffer is 16 bytes. Using snprintf() with sizeof()
ensures the buffer cannot overflow regardless of the integer value.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>