ARM: keystone: Update compatible to have SoC specific matches

With future SoCs of keystone2 family, the generic compatible match
may not be sufficient to handle SoC specific handling. So introduce
matches based on SoC compatiblity.

Signed-off-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Santosh Shilimkar <ssantosh@kernel.org>