drm/amd: Don't initialize PSP twice for Navi3x

PSP functions are already set by psp_early_init() so initializing
them a second time is unnecessary.
No intended functional changes.

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