powerpc/e500v2: Add Power ISA properties to comply with ePAPR 1.1

power-isa-version and power-isa-* are cpu node general properties defined
in ePAPR.

If the power-isa-version property exists, then for each category from the
Categories section of Book I of the Power ISA version indicated, the
existence of a property named power-isa-[CAT], where [CAT] is the
abbreviated category name with all uppercase letters converted to
lowercase, indicates that the category is supported by the implementation.

The patch update all e500v2 platforms.

Signed-off-by: Liu Yu <yu.liu@freescale.com>
Signed-off-by: Olivia Yin <hong-hua.yin@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>