dm: extcon: add an uclass for extcon

Add a new simple uclass for extcon. Currently all setup is done
in the probe. Uclass struct and ops are empty for now.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig
new file mode 100644
index 0000000..8a50250
--- /dev/null
+++ b/drivers/extcon/Kconfig
@@ -0,0 +1,15 @@
+menu "Extcon Support"
+
+config EXTCON
+	bool "External Connector Class (extcon) support"
+	depends on DM
+	help
+	  Say Y here to enable external connector class (extcon) support.
+	  This allows monitoring external connectors and supports external
+	  connectors with multiple states; i.e., an extcon that may have
+	  multiple cables attached. For example, an external connector
+	  of a device may be used to connect an HDMI cable and a AC adaptor,
+	  and to host USB ports. Many of 30-pin connectors including PDMI
+	  are also good examples.
+
+endmenu