drm/amd/pp: Drop wrapper functions for upper/lower_32_bits

replace smu_upper_32_bits/smu_lower_32_bits with
the standard kernel macros

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>