drm: bridge: it66121: Check drm_bridge_attach retval

The return value of drm_bridge_attach() is ignored during
the it66121_bridge_attach() call, which is incorrect.

Fixes: 988156dc ("drm: bridge: add it66121 driver")
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210805185039.402178-1-robert.foss@linaro.org
Link: https://patchwork.freedesktop.org/patch/msgid/20210805185039.402178-1-robert.foss@linaro.org

drivers/gpu/drm/bridge/ite-it66121.c

@@ -536,6 +536,8 @@ static int it66121_bridge_attach(struct drm_bridge *bridge,
 		return -EINVAL;
 
 	ret = drm_bridge_attach(bridge->encoder, ctx->next_bridge, bridge, flags);
+	if (ret)
+		return ret;
 
 	ret = regmap_write_bits(ctx->regmap, IT66121_CLK_BANK_REG,
 				IT66121_CLK_BANK_PWROFF_RCLK, 0);