drm/amd/display: Separate hardware initialization from creation

[Why]
Separating the hardware initialization from the creation of the
dc structures gives greater flexibility to the dm to override
options for debugging.

[How]
Move the hardware initialization call to a new function,
dc_hardware_init. No functional change is intended.

Signed-off-by: Julian Parkin <julian.parkin@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Acked-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>