drm/amd/display: safeguard compressor api

Only call compressor api if it's available.
Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dce110/dce110_hw_sequencer.c

@@ -1185,6 +1185,7 @@ static void power_down_all_hw_blocks(struct core_dc *dc)
 	power_down_clock_sources(dc);
 
 #ifdef ENABLE_FBC
+	if (dc->fbc_compressor)
 		dc->fbc_compressor->funcs->disable_fbc(dc->fbc_compressor);
 #endif
 }
@@ -1658,6 +1659,7 @@ enum dc_status dce110_apply_ctx_to_hw(
 	set_safe_displaymarks(&context->res_ctx, dc->res_pool);
 
 #ifdef ENABLE_FBC
+	if (dc->fbc_compressor)
 		dc->fbc_compressor->funcs->disable_fbc(dc->fbc_compressor);
 #endif
 	/*TODO: when pplib works*/
@@ -2246,6 +2248,7 @@ static void init_hw(struct core_dc *dc)
 		abm->funcs->abm_init(abm);
 	}
 #ifdef ENABLE_FBC
+	if (dc->fbc_compressor)
 		dc->fbc_compressor->funcs->power_up_fbc(dc->fbc_compressor);
 #endif
 }