drm/amd/display: Fix a potential buffer overflow in 'dp_dsc_clock_en_read()'

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix a potential buffer overflow in 'dp_dsc_clock_en_read()' Tell snprintf() to store at most 10 bytes in the output buffer instead of 30. Fixes the below: drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm_debugfs.c:1508 dp_dsc_clock_en_read() error: snprintf() is printing too much 30 vs 10