Swift power supply presence detects

PS0 uses the same GPIO that witherspoon uses, but PS1
uses GPIOR7 (143).

Tested: Built both images, made sure the correct conf files
        showed up in rootfs.

Signed-off-by: Matt Spinler <spinler@us.ibm.com>
Change-Id: Id12161a921e68ce44a2a74181b4eeda1ff41d916
3 files changed