drm/amdgpu: only init tap_delay ucode when it's included in ucode binary

Not all the gfx10 variants need to integrate
global tap_delay and per se tap_delay firmwares

Only init tap_delay ucode when it does include in
rlc ucode binary so driver doesn't send a null buffer
to psp for firmware loading

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Jack Gui <Jack.Gui@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>