Enable or disable the power button in Kconfig

Some mainboards need to disable the power button to avoid turning off
right after being turned on, while other boards ship with a jumper over
the power button and should allow the user to configure the behavior.

This adds infrastructure in the form of four mutually exclusive options
which can be selected in a mainboard Kconfig (power button forced on/off,
and user-controllable with default on/off) and one result bool which
source code can test. (Enable the button or not.)

The options have been implemented in CS5536 code and for all mainboards
which select SOUTHBRIDGE_AMD_CS5536, but should be used also by other
chipsets where applicable. Note that if chipset code uses the result
bool ENABLE_POWER_BUTTON, then every board using that chipset must
select one out of the four control options in order to build.

All touched boards should have unchanged behavior, except
pcengines/alix1c, traverse/geos and lippert/hurricane-lx where the
power button can now be configured by the user.

Build tested for alix1c, alix2d, hurricane-lx and wyse-s50. Confirmed
to work as advertised on alix1c both with button enabled and disabled.

Includes additional traverse/geos changes from Nathan and
lippert/hurricane-lx changes from Jens to correctly use the new
feature on those boards.

Signed-off-by: Peter Stuge <peter@stuge.se>
Acked-by: Aurelien Guillaume <aurelien@iwi.me>
Acked-by: Nils Jacobs <njacobs8@hetnet.nl>


git-svn-id: svn://svn.coreboot.org/coreboot/trunk@5948 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
diff --git a/src/mainboard/lippert/roadrunner-lx/Kconfig b/src/mainboard/lippert/roadrunner-lx/Kconfig
index 44326d1..4e29742 100644
--- a/src/mainboard/lippert/roadrunner-lx/Kconfig
+++ b/src/mainboard/lippert/roadrunner-lx/Kconfig
@@ -13,6 +13,7 @@
 	# Standard chip is a 512 KB FWH. Replacing it with a 1 MB
 	# SST 49LF008A is possible.
 	select BOARD_ROMSIZE_KB_512
+	select POWER_BUTTON_FORCE_ENABLE
 
 config MAINBOARD_DIR
 	string