Update the AM65x HwSpinlock example to fix couple of warnings
that started showing up after the conversion of K3 bindings to
YAML format in commit 66e06509 ("dt-bindings: arm: ti:
Convert K3 board/soc bindings to DT schema").

 compatible: ['ti,am654'] is not valid under any of the given schemas (Possible causes of the failure):
 compatible: ['ti,am654'] is too short
 compatible:0: 'ti,am654' is not one of ['ti,am654-evm']

Also, fix one of the node names while at this.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Suman Anna <s-anna@ti.com>
Link: https://lore.kernel.org/r/20200928225155.12432-1-s-anna@ti.comSigned-off-by: Rob Herring <robh@kernel.org>