drm/amdgpu: Convert SMU version to decimal in debugfs

This is more useful when talking to the SMU team to have the information
in this format, save one less step to manually do it.

Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>