drm/amd/display: Check hw_init state when determining if DMCUB is initialized

[Why]
CW2 may already be programmed when coming back from S4. In this case
we want to unconditionally replace whatever DMCUB version is currently
enabled with the latest.

[How]
Check the hw_init flag to know whether or not we've previously executed
the initliazed routine.

Signed-off-by: Nicholas Kazlauskas <[e-mail]>
Reviewed-by: Tony Cheng <[e-mail]>
Acked-by: Bhawanpreet Lakha <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/display/dmub/src/dmub_srv.c

···
 	if (!dmub->sw_init)
 		return DMUB_STATUS_INVALID;
 
+	if (!dmub->hw_init)
+		return DMUB_STATUS_OK;
+
 	if (dmub->hw_funcs.is_hw_init)
 		*is_hw_init = dmub->hw_funcs.is_hw_init(dmub);