drm/bridge: Select DRM_KMS_HELPER for DRM_PANEL_BRIDGE

drm/bridge: Select DRM_KMS_HELPER for DRM_PANEL_BRIDGE

Since the kconfig symbol of DRM_PANEL_BRIDGE is only adding
bridge/panel.o to drm_kms_helper object, we need to select
DRM_KMS_HELPER to make sure the file is actually getting built.

Otherwise with certain defconfigs e.g. devm_drm_of_get_bridge will not
be properly available:

  aarch64-linux-gnu-ld: drivers/phy/qualcomm/phy-qcom-qmp-combo.o: in function `qmp_combo_bridge_attach':
  drivers/phy/qualcomm/phy-qcom-qmp-combo.c:3204:(.text+0x8f4): undefined reference to `devm_drm_of_get_bridge'

Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Link: https://lore.kernel.org/r/20240111-drm-panel-bridge-fixup-v1-1-e06292f6f500@fairphone.com
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240111-drm-panel-bridge-fixup-v1-1-e06292f6f500@fairphone.com