ARM: OMAP2+: Add checks for device tree based sysconfig data

We can check the device tree based sysconfig data against the existing
platform data to make sure we're not introducing regressions. Then at
some point after the sysconfig data comes from device tree, we can just
drop the related platform data.

Cc: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>