board: drop old --uboot igepv2 option

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
board: drop old --uboot mx6qsabrelite option

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
board: drop old --uboot crane option

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>