PCC: Disable compilation by default

PCC is made selectable only by clients which use it. e.g. CPPC
Default it to disabled so that it is not included accidentally on
platforms which dont use it.
Signed-off-by: NAshwin Chaugule <ashwin.chaugule@linaro.org>
Reviewed-by: NAl Stone <al.stone@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/mailbox/Kconfig

@@ -46,6 +46,7 @@ config OMAP_MBOX_KFIFO_SIZE
 config PCC
 	bool "Platform Communication Channel Driver"
 	depends on ACPI
+	default n
 	help
 	  ACPI 5.0+ spec defines a generic mode of communication
 	  between the OS and a platform such as the BMC. This medium