API: Add public counter API

Add the public API for counter devices and the drivers infrastructure.

Origin: Original

Change-Id: If100fbc9b3d119ce2be6c131bd64dbeb4fe346f2
Signed-off-by: Baohong Liu <baohong.liu@intel.com>
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 732050f..23fd73b 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -71,4 +71,6 @@
 
 source "drivers/sensor/Kconfig"
 
+source "drivers/counter/Kconfig"
+
 endmenu