optee: Add optee as a machine feature to all supported boards
Currently we assume that all qoriq arm64 boards support optee, however
that might not be the case for boards added by other layers building
on top of meta-freescale. To better support this case add a machine
feature to indicate if a given machine has optee support.
Add the new optee feature to all qoriq arm64 except ls2080ardb as it
doesn't seems to be supported by optee.
