PowerCap: Add class driver

The power capping framework providing a consistent interface between the
kernel and user space that allows power capping drivers to expose their
settings to user space in a uniform way.
The overall design of the framework is described in the documentation
added by the previous patch in this series.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/powercap/Makefile b/drivers/powercap/Makefile
new file mode 100644
index 0000000..6defbc8
--- /dev/null
+++ b/drivers/powercap/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_POWERCAP)	+= powercap_sys.o