drm/amd/pm: Fix warnings

Fixes warnings:

drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu13/smu_v13_0_6_ppt.c:286:45:
warning: '%s' directive output may be truncated writing up to 29 bytes
into a region of size 23 [-Wformat-truncation=]
drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu13/smu_v13_0_6_ppt.c:286:52:
warning: '%s' directive output may be truncated writing up to 29 bytes
into a region of size 23 [-Wformat-truncation=]
drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu14/smu_v14_0.c:72:45: warning:
'%s' directive output may be truncated writing up to 29 bytes into a
region of size 23 [-Wformat-truncation=]
drivers/gpu/drm/amd/amdgpu/../pm/swsmu/smu14/smu_v14_0.c:72:52: warning:
'%s' directive output may be truncated writing up to 29 bytes into a
region of size 23 [-Wformat-truncation=]

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Yang Wang <kevinyang.wang@amd.com>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>