drm/display: fix kerneldocs references

The commit 9da7ec9b19d8 ("drm/bridge-connector: move to
DRM_DISPLAY_HELPER module") changed location of the
drm_bridge_connector.c file, but didn't update the kerneldocs. Fix that.

Fixes: 9da7ec9b19d8 ("drm/bridge-connector: move to DRM_DISPLAY_HELPER module")
Reported-by: Stephen Rothwell <[e-mail]>
Closes: https://lore.kernel.org/dri-devel/[e-mail]/
Acked-by: Thomas Zimmermann <[e-mail]>
Reviewed-By: Carlos Bilbao <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Dmitry Baryshkov <[e-mail]>

Documentation/gpu/drm-kms-helpers.rst

···
 Bridge Connector Helper
 -----------------------
 
-.. kernel-doc:: drivers/gpu/drm/drm_bridge_connector.c
+.. kernel-doc:: drivers/gpu/drm/display/drm_bridge_connector.c
    :doc: overview
 
 
···
 Bridge Connector Helper Reference
 ---------------------------------
 
-.. kernel-doc:: drivers/gpu/drm/drm_bridge_connector.c
+.. kernel-doc:: drivers/gpu/drm/display/drm_bridge_connector.c
    :export:
 
 Panel-Bridge Helper Reference