drm/bridge: anx7625: Fix refcount bug in anx7625_parse_dt()

In anx7625_parse_dt(), 'pdata->mipi_host_node' will be assigned a
new reference with of_graph_get_remote_node() which will increase
the refcount of the object, correspondingly, we should call
of_node_put() for the old reference stored in the 'pdata->mipi_host_node'.

Fixes: 8bdfc5da ("drm/bridge: anx7625: Add anx7625 MIPI DSI/DPI to DP")
Signed-off-by: Liang He <windhl@126.com>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220719065447.1080817-1-windhl@126.com