[coreboot] [PATCH] Enable or disable the power button in Kconfig

[Peter Stuge]

Please see the attached patch. I would like to especially ask those
who have worked on boards which use the 5536 to check if maybe their
board should select a different POWER_BUTTON_* now. Again, existing
behavior should be unchanged from previous except on ALIX.1.

Jens, please confirm if my understanding of the old vs. new
hurricane-lx board version vs. power button behavior is correct.

Thanks!

//Peter