PowerCap: Add to drivers Kconfig and Makefile

Added changes to Makefile and Kconfig to include in driver build.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/Kconfig b/drivers/Kconfig
index aa43b91..969e987 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -166,4 +166,6 @@
 
 source "drivers/fmc/Kconfig"
 
+source "drivers/powercap/Kconfig"
+
 endmenu