beagleboard: enable HUB power on all variants of the BeagleBoard

beagleboard: enable HUB power on all variants of the BeagleBoard

Changes made by Jason Kridner with inputs from Eric Benard to special case xM Rev A and xM Rev B

Relevant discussions:
http://www.mail-archive.com/[email protected]/msg59361.html
http://www.mail-archive.com/[email protected]/msg59589.html

Signed-off-by: Joel A Fernandes <[email protected]>
Cc: Eric Benard <[email protected]>
Cc: Christian Spielberger <[email protected]>
Cc: Jason Kridner <[email protected]>
Signed-off-by: Sandeep Paulraj <[email protected]>