dt-bindings: hwlock: omap: Convert binding to YAML

dt-bindings: hwlock: omap: Convert binding to YAML

Convert the current OMAP hwspinlock binding from text format to YAML
format/DT schema, and delete the legacy text binding file.

The new YAML binding conversion is a slightly updated version compared
to the original. The legacy "ti,hwmods" property is now obsolete and
is dropped altogether, and the K3 example is updated to showcase the
actual dts node usage.

Signed-off-by: Suman Anna <s-anna@ti.com>
Link: https://lore.kernel.org/r/20200828041447.5900-1-s-anna@ti.com
Signed-off-by: Rob Herring <robh@kernel.org>