drm/amd/display: Handle dml allocation failure to avoid crash

[Why]
In the case where a dml allocation fails for any reason, the
current state's dml contexts would no longer be valid. Then
subsequent calls dc_state_copy_internal would shallow copy
invalid memory and if the new state was released, a double
free would occur.

[How]
Reset dml pointers in new_state to NULL and avoid invalid
pointer

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Ryan Seto <ryanseto@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: Ryan Seto

drivers/gpu/drm/amd/display/dc/core/dc_state.c

@@ -265,6 +265,9 @@ struct dc_state *dc_state_create_copy(struct dc_state *src_state)
 	dc_state_copy_internal(new_state, src_state);
 
 #ifdef CONFIG_DRM_AMD_DC_FP
+	new_state->bw_ctx.dml2 = NULL;
+	new_state->bw_ctx.dml2_dc_power_source = NULL;
+
 	if (src_state->bw_ctx.dml2 &&
 			!dml2_create_copy(&new_state->bw_ctx.dml2, src_state->bw_ctx.dml2)) {
 		dc_state_release(new_state);